ccna-quizlist.docx

Quizzes ======= Chapter 1 --------- ### **1.** Which of the following protocols are examples of TCP/IP transport layer protocols? (Choose two answers.) ### Ans **1.** D and F. Of the remaining answers, Ethernet defines both physical and data-link protocols, PPP is a data-link protocol, IP is a network layer protocol, and SMTP and HTTP are application layer protocols. ### **2.** Which of the following protocols are examples of TCP/IP data-link layer protocols? (Choose two answers.) ### Ans **2.** A and G. Of the remaining answers, IP is a network layer protocol, TCP and UDP are transport layer protocols, and SMTP and HTTP are application layer protocols. ### **3.** The process of HTTP asking TCP to send some data and making sure that it is received correctly is an example of what? ### Ans **3.** B. Adjacent-layer interaction occurs on one computer, with two adjacent layers in the model. The higher layer requests services from the next lower layer, and the lower layer provides the services to the next higher layer. ### **4.** The process of TCP on one computer marking a TCP segment as segment 1, and the receiving computer then acknowledging the receipt of TCP segment 1 is an example of what? ### Ans **4.** B. Same-layer interaction occurs on multiple computers. The functions defined by that layer typically need to be accomplished by multiple computers---for example, the sender setting a sequence number for a segment and the receiver acknowledging receipt of that segment. A single layer defines that process, but the implementation of that layer on multiple devices is required to accomplish the function. ### **5.** The process of a web server adding a TCP header to the contents of a web page, followed by adding an IP header and then adding a data-link header and trailer, is an example of what? ### Ans **5.** A. Encapsulation is defined as the process of adding a header in front of data supplied by a higher layer (and possibly adding a trailer as well). ### **6.** Which of the following terms is used specifically to identify the entity created when encapsulating data inside data-link layer headers and trailers? ### Ans **6. D.** By convention, the term *frame* refers to the part of a network message that includes the data-link header and trailer, with encapsulated data. The term *packet* omits the data-link header and trailer, leaving the network layer header with its encapsulated data. The term *segment* omits the network layer header, leaving the transport layer header and its encapsulated data. ### **7.** Which OSI encapsulation term can be used instead of the term frame? ### Ans **7.** B. The term frame refers to the data-link (that is, Layer 2) data structure created by a Layer 2 protocol. As a result, the matching OSI term for protocol data units (PDUs) mentions that same layer, that is, Layer 2 PDU, or L2PDU. ### Chapter 2 ### **1.** In the LAN for a small office, some user devices connect to the LAN using a cable, while others connect using wireless technology (and no cable). Which of the following is true regarding the use of Ethernet in this LAN? ### Ans **1.** A. The IEEE defines Ethernet LAN standards, with standard names that begin with 802.3, all of which happen to use cabling. The IEEE also defines wireless LAN standards, with standard names that begin with 802.11, which are separate standards from Ethernet. ### **2.** Which of the following Ethernet standards defines Gigabit Ethernet over UTP cabling? ### Ans **2.** C. The number before the word *BASE* defines the speed, in megabits per second (Mbps). 1000 Mbps equals 1 gigabit per second (1 Gbps). The *T* in the suffix implies twisted-pair or UTP cabling, so 1000BASE-T is the UTP-based Gigabit Ethernet standard name. ### **3.** Which of the following is true about Ethernet crossover cables for Fast Ethernet? ### Ans **3.** B. Crossover cables cross the wire at one node's transmit pin pair to the different pins used as the receive pins on the other device. For 10- and 100-Mbps Ethernet, the specific crossover cable wiring connects the pair at pins 1 and 2 on each end of the cable to pins 3 and 6 on the other end of the cable, respectively. ### **4.** Each answer lists two types of devices used in a 100BASE-T network. If these devices were connected with UTP Ethernet cables, which pairs of devices would require a straight-through cable? (Choose three answers.) ### Ans **4.** B, D, and E. Routers, wireless access point Ethernet ports, and PC NICs all send using pins 1 and 2, whereas hubs and LAN switches transmit on pins 3 and 6. Straightthrough cables connect devices that use opposite pin pairs for sending, because the cable does not need to cross the pairs. ### 5. Which of the following are advantages of using multimode fiber for an Ethernet link instead of UTP or single-mode fiber? ### Ans **5.** B. Multimode fiber works with LED-based transmitters rather than laser-based transmitters. Two answers mention the type of transmitters, making one of those answers correct and one incorrect. Two answers mention distance. The answer that mentions the longest distance possible is incorrect because single-mode cables, not multimode cables, provide the longest distances. The other (correct) answer mentions the tradeoff of multimode being used for distances just longer than UTP's 100 meter limit, while happening to use less expensive hardware than single mode. ### 6. Which of the following is true about the CSMA/CD algorithm? ### Ans **6.** B. NICs (and switch ports) use the carrier sense multiple access with collision detection (CSMA/CD) algorithm to implement half-duplex logic. CSMA/CD attempts to avoid collisions, but it also notices when collisions do occur, with rules about how the Ethernet nodes should stop sending, wait, and try again later. ### 7. Which of the following is true about the Ethernet FCS field? ### Ans **7.** C. The 4-byte Ethernet FCS field, found in the Ethernet trailer, allows the receiving node to see what the sending node computed with a math formula that is a key part of the error-detection process. Note that Ethernet defines the process of detecting errors (error detection), but not error recovery. ### 8. Which of the following are true about the format of Ethernet addresses? (Choose three answers.) ### Ans **8.** B, C, and E. The pre-assigned universal MAC address, given to each Ethernet port when manufactured, breaks the address into two 3-byte halves. The first half is called the organizationally unique identifier (OUI), which the IEEE assigns to the company that builds the product as a unique hex number to be used only by that company. ### 9. Which of the following terms describe Ethernet addresses that can be used to send one frame that is delivered to multiple devices on the LAN? (Choose two answers.) ### Ans **9.** C and D. Ethernet supports unicast addresses, which identify a single Ethernet node, and group addresses, which can be used to send one frame to multiple Ethernet nodes. The two types of group addresses are the *broadcast address* and *multicast address*. ### Chapter 3 **1. Which of the following fields in the HDLC header used by Cisco routers does Cisco** **add, beyond the ISO standard HDLC?** ### Ans **1.** B. The standard HDLC header does not include a Type field, which identifies the type of packet encapsulated inside the HDLC frame. ### 2. Two routers, R1 and R2, connect using an Ethernet over MPLS service. The service **provides point-to-point service between these two routers only, as a Layer 2 Ethernet service. Which of the following are the most likely to be true about this WAN? (Choose two answers.)** ### Ans **2.** B and D. The physical installation uses a model in which each router uses a physical Ethernet link to connect to some SP device in an SP facility called a point of presence (PoP). The Ethernet link does not span from each customer device to the other. From a data-link perspective, both routers use the same Ethernet standard header and trailer used on LANs; HDLC does not matter on these Ethernet WAN links. ### 3. Imagine a network with two routers that are connected with a point-to-point HDLC **serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1 and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true?** ### Ans **3.** A. PC1 will send an Ethernet frame to Router 1, with PC1's MAC address as the source address and Router 1's MAC address as the destination address. Router 1 will remove the encapsulated IP packet from that Ethernet frame, discarding the frame header and trailer. Router 1 will forward the IP packet by first encapsulating it inside an HDLC frame, but Router 1 will not encapsulate the Ethernet frame in the HDLC frame but rather the IP packet. Router 2 will de-encapsulate the IP packet from the HDLC frame and forward it onto the Ethernet LAN, adding a new Ethernet header and trailer, but this header will differ. It will list Router 2's MAC address as the source address and PC2's MAC address as the destination address. ### 4. Which of the following does a router normally use when making a decision about **routing TCP/IP packets?** ### Ans **4.** C. Routers compare the packet's destination IP address to the router's IP routing table, making a match and using the forwarding instructions in the matched route to forward the IP packet. ### **5.** Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices? ### Ans **5.** C. IPv4 hosts generally use basic two-branch logic. To send an IP packet to another host on the same IP network or subnet that is on the same LAN, the sender sends the IP packet directly to that host. Otherwise, the sender sends the packet to its default router (also called the default gateway). ### **6.** Which of the following are functions of a routing protocol? (Choose two answers.) ### Ans **6.** A and C. Routers do all the actions listed in all four answers; however, the routing protocol does the functions in the two listed answers. Independent of the routing protocol, a router learns routes for IP subnets and IP networks directly connected to its interfaces. Routers also forward (route) IP packets, but that process is called IP routing, or IP forwarding, and is an independent process compared to the work of a routing protocol. ### **7.** A company implements a TCP/IP network, with PC1 sitting on an Ethernet LAN. Which of the following protocols and features requires PC1 to learn information from some other server device? ### Ans **7.** C. Address Resolution Protocol (ARP) does allow PC1 to learn information, but the information is not stored on a server. The **ping** command does let the user at PC1 learn whether packets can flow in the network, but it again does not use a server. With the Domain Name System (DNS), PC1 acts as a DNS client, relying on a DNS server to respond with information about the IP addresses that match a given hostname. ### Chapter 4 **Foundation Topics Section Questions** - Wide-Area Networks 1, 2 - IP Routing 3--6 - Other Network Layer Functions 7 ### **1.** Which of the following fields in the HDLC header used by Cisco routers does Cisco add, beyond the ISO standard HDLC? ### Ans **1.** A and B. The command in the question is an EXEC command that happens to require only user mode access. As such, you can use this command in both user mode and enable mode. Because it is an EXEC command, you cannot use the command (as shown in the question) in configuration mode. Note that you can put the word **do** in front of the EXEC command while in configuration mode (for example, **do show mac** **address-table**) to issue the command from inside any configuration mode. ### **2.** Two routers, R1 and R2, connect using an Ethernet over MPLS service. The service provides point-to-point service between these two routers only, as a Layer 2 Ethernet service. Which of the following are the most likely to be true about this WAN? (Choose two answers.) ### Ans **2.** B. The command referenced in the question, the **reload** command, is an EXEC command that happens to require privileged mode, also known as enable mode. This command is not available in user mode. Note that you can put the word **do** in front of the EXEC command while in configuration mode (for example, **do reload**) to issue the command from inside any configuration mode. ### **3.** Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1 and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true? ### Ans **3.** B. SSH provides a secure remote login option, encrypting all data flows, including password exchanges. Telnet sends all data (including passwords) as clear text. ### **4.** Which of the following does a router normally use when making a decision about routing TCP/IP packets? ### Ans **4.** A. Switches (and routers) keep the currently used configuration in RAM, using NVRAM to store the configuration file that is loaded when the switch (or router) next loads the IOS. ### **5.** Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices? ### Ans **5.** F. The startup-config file is in NVRAM, and the running-config file is in RAM. ### **6.** Which of the following are functions of a routing protocol? (Choose two answers.) ### Ans **6.** B and C. The **exit** command moves the user one config mode backward, toward global configuration mode, or if already in global configuration mode, it moves the user back to enable mode. From console mode, it moves the user back to global configuration mode. The **end** command and the Ctrl+Z key sequence both move the user back to enable mode regardless of the current configuration submode. ### Chapter 5 **Foundation Topics Section Questions** - LAN Switching Concepts 1--4 - Verifying and Analyzing Ethernet Switching 5--6 ### 1. Which of the following statements describes part of the process of how a switch decides to forward a frame destined for a known unicast MAC address? ### Ans **1.** A. A switch compares the destination MAC address to the MAC address table. If a matching entry is found, the switch forwards the frame out the appropriate interface. If no matching entry is found, the switch floods the frame. ### 2. Which of the following statements describes part of the process of how a LAN switch decides to forward a frame destined for a broadcast MAC address? ### Ans **2.** C. A switch floods broadcast frames, multicast frames (if no multicast optimizations are enabled), and unknown unicast destination frames (frames whose destination MAC address is not in the MAC address table). ### 3. Which of the following statements best describes what a switch does with a frame **destined for an unknown unicast address?** ### Ans **3.** A. A switch floods broadcast frames, multicast frames (if no multicast optimizations are enabled), and unknown unicast destination frames (frames whose destination MAC address is not in the MAC address table). ### 4. Which of the following comparisons does a switch make when deciding whether a new MAC address should be added to its MAC address table? ### Ans **4.** B. Switches need to learn the location of each MAC address used in the LAN relative to that local switch. When a switch receives a frame, the source MAC identifies the sender. The interface in which the frame arrives identifies the local switch interface closest to that node in the LAN topology. ### 5. A Cisco Catalyst switch has 24 10/100 ports, numbered 0/1 through 0/24. Ten PCs connect to the 10 lowest numbered ports, with those PCs working and sending data over the network. The other ports are not connected to any device. Which of the following answers lists facts displayed by the show interfaces status command? ### Ans **5.** C. The **show interfaces status** command lists one line of output per interface. Cisco Catalyst switches name the type of interface based on the fastest speed of the interface, so 10/100 interfaces would be Fast Ethernet. With a working connection, ports from FastEthernet 0/1 through 0/10 would be listed in a connected state, while the rest would be listed in a notconnected state. ### 6. Consider the following output from a Cisco Catalyst switch: SW1\# show mac address-table dynamic Mac Address Table \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- Vlan Mac Address Type Ports \-\-\-- \-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-- \-\-\-\-- 1 02AA.AAAA.AAAA DYNAM IC Gi0/1 1 02BB.BBBB.BBBB DYNAMIC Gi0/2 1 02CC.CCCC.CCCC DYNAMIC Gi0/3 Total Mac Addresses for this criterion: 3 **Which of the following answers is true about this switch?** ### Ans **6.** D. For the correct answer, each entry lists the learned MAC address. By definition, dynamically learned MAC addresses are learned by looking at the source MAC address of received frames. (That fact rules out one of the incorrect answers as well.) The **show mac address-table dynamic** command lists the current list of MAC table entries, with three known entries at the point at which the command output was gathered. The counter in the last line of output lists the number of current entries, not the total number of learned MAC addresses since the last reboot. For instance, the switch could have learned other MAC addresses whose entries timed out from the MAC address table. Finally, the answer that claims that port Gi0/2 connects directly to a device with a particular MAC address may or may not be true. That port could connect to another switch, and another, and so on, with one of those switches connecting to the device that uses the listed MAC address. ### Chapter 6 **Foundation Topics Section Questions** - Securing the Switch CLI 1--3 - Enabling IP for Remote Access 4--5 - Miscellaneous Settings Useful in Lab 6 ### 1. Imagine that you have configured the enable secret command, followed by the enable password command, from the console. You log out of the switch and log back in at the console. Which command defines the password that you had to enter to access privileged mode? ### Ans **1.** B. If both commands are configured, IOS accepts only the password as configured in the **enable secret** command. **2. An engineer wants to set up simple password protection with no usernames for some switches in a lab, for the purpose of keeping curious coworkers from logging in to the lab switches from their desktop PCs. Which of the following commands would be a useful part of that configuration?** ### Ans **2.** A. To answer this question, it might be best to first think of the complete configuration and then find any answers that match the configuration. The commands, in vty line configuration mode, would be **password** *password* and **login**. Only one answer lists a vty subcommand that is one of these two commands. Of note in the incorrect answers: One answer mentions console subcommands. The console does not define what happens when remote users log in; those details sit in the vty line configuration. One answer mentions the **login local** command; this command means that the switch should use the local list of configured usernames/passwords. The question stated that the engineer wanted to use passwords only, with no usernames. One answer mentions the **transport input ssh** command, which, by omitting the **telnet** keyword, disables Telnet. While that command can be useful, SSH does not work when using passwords only; SSH requires both a username and a password. So, by disabling Telnet (and allowing SSH only), the configuration would allow no one to remotely log in to the switch. ### 3. An engineer had formerly configured a Cisco 2960 switch to allow Telnet access so that the switch expected a password of mypassword from the Telnet user. The engineer then changed the configuration to support Secure Shell. Which of the following commands could have been part of the new configuration? (Choose two answers.) ### ans **3.** B and C. SSH requires the use of usernames in addition to a password. Using the **username** global command would be one way to define usernames (and matching passwords) to support SSH. The vty lines would also need to be configured to require the use of usernames, with the **login local** vty subcommand being one such option. The **transport input ssh** command could be part of a meaningful configuration, but it is not a global configuration command (as claimed in one wrong answer). Likewise, one answer refers to the **username** command as a command in vty config mode, which is also the wrong mode. ### 4. An engineer's desktop PC connects to a switch at the main site. A router at the main site connects to each branch office through a serial link, with one small router and switch at each branch. Which of the following commands must be configured on the branch office switches, in the listed configuration mode, to allow the engineer to telnet to the branch office switches and supply only a password to login? (Choose three answers.) ### ans **4.** A, D, and F. To allow access through Telnet, the switch must have password security enabled, at a minimum using the **password** vty line configuration subcommand. In addition, the switch needs an IP address (configured under one VLAN interface) and a default gateway when the switch needs to communicate with hosts in a different subnet. ### 5. A Layer 2 switch configuration places all its physical ports into VLAN 2. The IP **addressing plan shows that address 172.16.2.250 (with mask 255.255.255.0) is reserved for use by this new LAN switch and that 172.16.2.254 is already configured on the router connected to that same VLAN. The switch needs to support SSH connections into the switch from any subnet in the network. Which of the following commands are part of the required configuration in this case? (Choose two answers.)** ### Ans **5.** B and C. To allow SSH or Telnet access, a switch must have a correct IP configuration. That includes the configuration of a correct IP address and mask on a VLAN interface. That VLAN interface then must have a path out of the switch via ports assigned to that VLAN. In this case, with all ports assigned to VLAN 2, the switch must use interface VLAN 2 (using the **interface vlan 2** configuration command). To meet the requirement to support login from hosts outside the local subnet, the switch must configure a correct default gateway setting with the **ip default-gateway** **172.16.2.254** global command in this case. **6. Which of the following line subcommands tells a switch to wait until a show command's output has completed before displaying log messages on the screen?** ### ans **6.** A. The **logging synchronous** line subcommand synchronizes the log message display with other command output so the log message does not interrupt a **show** command's output. The **no ip domain-lookup** command is not a line subcommand. The other two incorrect answers are line subcommands but do not configure the function listed in the question. ### Chapter 7 **Foundation Topics Section Questions** - Configuring Switch Interfaces 1--3 - Analyzing Switch Interface Status and Statistics 4--6 ### 1. Which of the following describes a way to disable IEEE standard autonegotiation on a 10/100 port on a Cisco switch? ### ans **1.** F. Cisco switches do not have a command to disable autonegotiation of speed and duplex. Instead, a switch port that has both **speed** and **duplex** configured disables autonegotiation. ### 2. In which of the following modes of the CLI could you configure the duplex setting for interface Fast Ethernet 0/5? ### ans **2.** E. Cisco switches can be configured for speed (with the **speed** command) and duplex (with the **duplex** command) in interface configuration mode. ### 3. A Cisco Catalyst switch connects with its Gigabit0/1 port to an end user's PC. The end user, thinking the user is helping, manually sets the PC's OS to use a speed of 1000 Mbps and to use full duplex, and disables the use of autonegotiation. The switch's G0/1 port has default settings for speed and duplex. What speed and duplex settings will the switch decide to use? (Choose two answers.) ### ans **3.** A and D. The IEEE autonegotiation rules dictate that if a device attempts autonegotiation but the other side does not participate, use the slowest speed it supports. However, Cisco switches override that logic, instead sampling the electrical signal to detect the speed used by the connected device, so the switch will operate at 1000 Mbps. The switch uses the IEEE default setting for duplex based on the speed, and the IEEE default for duplex when using 1000 Mbps is to use full duplex. So in this case, the switch will match both the speed and the duplex setting made on the PC. ### 4. The output of the show interfaces status command on a 2960 switch shows interface Fa0/1 in a "disabled" state. Which of the following is true about interface Fa0/1? (Choose three answers.) ### Ans **4.** A, B, and D. The disabled state in the **show interfaces status** command is the same as an "administratively down and down" state shown in the **show interfaces** command. The interface must be in a connected state (per the **show interfaces status** command) before the switch can send frames out the interface. ### 5. Switch SW1 uses its Gigabit 0/1 interface to connect to switch SW2's Gigabit 0/2 interface. SW2's Gi0/2 interface is configured with the speed 1000 and duplex full commands. SW1 uses all defaults for interface configuration commands on its Gi0/1 interface. Which of the following are true about the link after it comes up? (Choose two answers.) ### Ans **5.** A and D. SW2 has effectively disabled IEEE standard autonegotiation by configuring both speed and duplex. However, Cisco switches can detect the speed used by the other device, even with autonegotiation turned off. Also, at 1 Gbps, the IEEE autonegotiation standard says to use full duplex. If the duplex setting cannot be negotiated, both ends use 1 Gbps, full duplex. ### 6. Switch SW1 connects via a cable to switch SW2's G0/1 port. Which of the following **conditions is the most likely to cause SW1's late collision counter to continue to increment?** ### Ans **6.** D. For the two answers about a duplex mismatch, that condition does cause collisions, particularly late collisions, but only the side using CSMA/CD logic (the half-duplex side) has any concept of collisions. So, if switch SW1 was using half duplex, and switch SW2 using full duplex, SW1 would likely see late collisions and see that counter increment over time. If switch SW2 had shut down its interface, switch SW1's interface would be in a down/down state, and none of the counters would increment. Also, if both switch ports had been configured with different speeds, again the ports would be in a down/down state, and none of the interface counters would increment. ### Chapter 8 **Foundation Topics Section Questions** - Virtual LAN Concepts 1--3 - VLAN and VLAN Trunking Configuration and Verification 4--6 - Troubleshooting VLANs and VLAN Trunks 7--8 ### 1. In a LAN, which of the following terms best equates to the term VLAN? ### ans **1.** B. A VLAN is a set of devices in the same Layer 2 broadcast domain. A subnet often includes the exact same set of devices, but it is a Layer 3 concept. A collision domain refers to a set of Ethernet devices, but with different rules than VLAN rules for determining which devices are in the same collision domain. ### 2. Imagine a switch with three configured VLANs. How many IP subnets are required, **assuming that all hosts in all VLANs want to use TCP/IP?** ### Ans **2.** D. Although a subnet and a VLAN are not equivalent concepts, the devices in one VLAN are typically in the same IP subnet and vice versa. ### 3. Switch SW1 sends a frame to switch SW2 using 802.1Q trunking. Which of the **answers describes how SW1 changes or adds to the Ethernet frame before forwarding the frame to SW2?** ### ans **3.** B. 802.1Q defines a 4-byte header, inserted after the original frame's destination and source MAC address fields. The insertion of this header does not change the original frame's source or destination address. The header itself holds a 12-bit VLAN ID field, which identifies the VLAN associated with the frame. ### 4. Imagine that you are told that switch 1 is configured with the dynamic auto parameter for trunking on its Fa0/5 interface, which is connected to switch 2. You have to configure switch 2. Which of the following settings for trunking could allow trunking to work? (Choose two answers.) ### Ans **4.** A and C. The **dynamic auto** setting means that the switch can negotiate trunking, but it can only respond to negotiation messages, and it cannot initiate the negotiation process. So, the other switch must be configured to trunk or to initiate the negotiation process (based on being configured with the **dynamic desirable** option). ### 5. A switch has just arrived from Cisco. The switch has never been configured with any **VLANs, but VTP has been disabled. An engineer configures the vlan 22 and name Hannahs-VLAN commands and then exits configuration mode. Which of the following are true? (Choose two answers.)** ### Ans **5.** A and B. The configured VTP setting of VTP transparent mode means that the switch can configure VLANs, so the VLAN is configured. In addition, the VLAN configuration details, including the VLAN name, show up as part of the running-config file. ### 6. Which of the following commands identify switch interfaces as being trunking interfaces: **interfaces that currently operate as VLAN trunks? (Choose two answers.)** ### ans **6.** B and C. The **show interfaces switchport** command lists both the administrative and operational status of each port. When a switch considers a port to be trunking, this command lists an operational trunking state of "trunk." The **show interfaces trunk** command lists a set of interfaces---the interfaces that are currently operating as trunks. So, both of these commands identify interfaces that are operational trunks. ### 7. In a switch that disables VTP, an engineer configures the commands vlan 30 and shutdown vlan 30. Which answers should be true about this switch? (Choose two **answers.)** ### Ans **7.** A and B. On switches that do not use VTP (by using VTP modes off or transparent), the switch lists all VLAN configuration in the configuration file (making one answer correct). Also, the **show vlan brief** command lists all defined VLANs, regardless of VTP mode and regardless of shutdown state. As a result, the two answers that mention commands are correct. The two incorrect answers are incorrect because VLAN 30 has been shut down, which means the switch will not forward frames in that VLAN, regardless of whether they arrive on access or trunk ports. ### 8. The show interfaces g0/1 trunk command provides three lists of VLAN IDs. Which **items would limit the VLANs that appear in the first of the three lists of VLANs?** ### ans **8.** B. The first list of VLAN IDs includes all VLANs (1--4094) except those overtly removed per the details in any **switchport trunk allowed vlan** interface subcommands on the trunk interface. If no such commands are configured, the first list in the output will include 1--4094. The two incorrect answers that mention VLAN 30 both list conditions that change the second of two lists of VLANs in the command output, while STP's choice to block an interface would impact the third list. ### Chapter 9 **Foundation Topics Section Questions** - STP and RSTP Basics 1--2 - Details Specific to STP (and Not RSTP) 3--4 - Rapid STP Concepts 5--7 ### 1. Which of the following port states are stable states used when STP has completed convergence? **(Choose two answers.)** ### ans **1.** A and B. Listening and learning are transitory port states, used only when moving from the blocking to the forwarding state. Discarding is not an STP port state. ### 2. Which of the following bridge IDs wins election as root, assuming that the switches with these bridge IDs are in the same network? ### ans **2.** C. The smallest numeric bridge ID wins the election. ### 3. Which of the following are transitory port states used only during the process of STP **convergence? (Choose two answers.)** ### ans **3.** C and D. Listening and learning are transitory port states used only when moving from the blocking to the forwarding state. Discarding is not an STP port state. Forwarding and blocking are stable states. ### 4. Which of the following facts determines how often a nonroot bridge or switch sends an STP Hello BPDU message? ### Ans **4.** B. Nonroot switches forward Hellos received from the root; the root sends these Hellos based on the root's configured Hello timer. ### 5. Which of the following RSTP port states have the same name and purpose as a port **state in traditional STP? (Choose two answers.)** ### ans **5.** B and D. RSTP uses port state forwarding, learning, and discarding. Forwarding and learning perform the same functions as the port states used by traditional STP. ### 6. RSTP adds features beyond STP that enable ports to be used for a role if another port **on the same switch fails. Which of the following statements correctly describe a port role that is waiting to take over for another port role? (Choose two answers.)** ### A **6.** A and D. With RSTP, an alternate port is an alternate to the root port when a switch's root port fails. A backup port takes over for a designated port if the designated port fails. ### 7. What STP feature causes an interface to be placed in the forwarding state as soon as the interface is physically active? ### a **7.** D. The PortFast feature allows STP to move a port from blocking to forwarding without going through the interim listening and learning states. STP allows this exception when the link is known to have no switch on the other end of the link, removing the risk of a switching loop. BPDU Guard is a common feature to use at the same time as PortFast because it watches for incoming bridge protocol data units (BPDU), which should not happen on an access port, and prevents the loops from a rogue switch by disabling the port. ### Chapter 10 **Foundation Topics Section Questions** - Understanding RSTP Through Configuration 1--3 - Implementing EtherChannel 4--6 **1. Which type value on the spanning-tree mode *type* global command enables the use** **of RSTP?** ### a **1.** A. Of the four answers, only **pvst** and **rapid-pvst** are valid options on the command. Of those, the **rapid-pvst** option enables Rapid Per VLAN Spanning Tree (RPVST+), which uses RSTP. The **pvst** option enables Per VLAN Spanning Tree (PVST) which uses STP, not RSTP. The other two options, if attempted, would cause the command to be rejected because the option does not exist. ### 2. Examine the following output from the show spanning-tree vlan 5 command, which describes a root switch in a LAN. Which answers accurately describe facts related to the root's bridge ID? SW1\# show spanning-tree vlan 5 VLAN0005 Spanning tree enabled protocol rstp Root ID Priority 32773 ### a **2.** A and C. The system ID extension (or extended system ID) part of a bridge ID contains 12 bits and sits after the 4-bit priority field and before the 48-bit system ID. Switches use this field to store the VLAN ID when using STP or RSTP to build spanning trees per VLAN. So of the two answers that mention the system ID extension, the one that lists the VLAN ID, in this case 5, is correct. The output also lists a priority of 32773. However, that output lists the decimal equivalent of the 16-bit priority value. In reality, this decimal value is the sum of the configured decimal priority plus the VLAN ID: 32768 + 5 = 32773. So in this case, the root's configured priority is 32,768. ### 3. With the Cisco RPVST+, which of the following action(s) does a switch take to identify which VLAN is described by a BPDU? (Choose three answers.) ### a **3.** A, B, and D. The Cisco Rapid Per VLAN Spanning Tree (RPVST+) creates one spanning tree instance per VLAN. To do so, it sends BPDUs per-VLAN. Each switch identifies itself with a unique Bridge ID (BID) per VLAN, made unique per-VLAN by adding the VLAN ID to the system ID extension 12-bit field of the BID. RVPST also adds a new Type-Length Value (TLV) to the BPDU itself, which includes a place to list the VLAN ID. Finally, when transmitting the BPDUs over VLAN trunks, the switch uses a trunking header that lists the VLAN ID (a practice sometimes called tunneling in 802.1Q.) The receiving switch can check all three locations that list the VLAN ID to ensure that they all agree about what VLAN the BPDU is describing. Of the four answers, the three correct answers describe the three actual locations in which RPVST+ lists the VLAN ID. ### 4. An engineer configures a switch to put interfaces G0/1 and G0/2 into the same Layer 2 **EtherChannel. Which of the following terms is used in the configuration commands?** ### a **4.** D. IOS uses the **channel-group** configuration command to create an EtherChannel. Then the term *etherchannel* is used in the **show etherchannel** command, which displays the status of the channel. The output of this **show** command then names the channel a *PortChannel*. The only answer that is not used somewhere in IOS to describe this multilink channel is *Ethernet-Channel*. ### 5. Which combinations of keywords on the channel-group interface subcommand on **two neighboring switches will cause the switches to use LACP and attempt to add the link to the EtherChannel? (Choose two answers.)** ### a **5.** B and D. The channel-group command will direct the switch to use LACP to dynamically negotiate to add a link to an EtherChannel when the command uses the **active** and **passive** keywords, respectively. The **desirable** and **passive** keywords direct the switch to use PaGP instead of LACP. Of the four answers, the two correct answers use two LACP values, while the two incorrect answers use at least one value that would cause the switch to use PaGP, making the answer incorrect. Of the two correct answers, both combinations result in the switches attempting to add the link to an EtherChannel using LACP as the negotiation protocol. If both switches used the **passive** keyword, they would both sit and wait for the other switch to begin sending LACP messages and therefore never attempt to add the link to the channel. ### 6. A Cisco Catalyst switch needs to send frames over a Layer 2 EtherChannel. Which **answer best describes how the switch balances the traffic over the four active links in the channel?** ### a **6.** C. EtherChannel load distribution, or load balancing, on Cisco Catalyst switches uses an algorithm. The algorithm examines some fields in the various headers, so messages that have the same values in those fields always flow over the same link in a particular EtherChannel. Note that it does not break the frames into smaller fragments nor use a round-robin approach that ignores the header values, and it does not examine link utilization when making the choice. ### Chapter 11 **Foundation Topics Section Questions** - Analyze Requirements 1--3 - Make Design Choices 4--7 ### 1. Host A is a PC, connected to switch SW1 and assigned to VLAN 1. Which of the following **are typically assigned an IP address in the same subnet as host A? (Choose two answers.)** ### a **1.** B and D. The general rule to determine whether two devices' interfaces should be in the same subnet is whether the two interfaces are separated from each other by a router. To provide a way for hosts in one VLAN to send data to hosts outside that VLAN, a local router must connect its LAN interface to the same VLAN as the hosts and have an address in the same subnet as the hosts. All the hosts in that same VLAN on the same switch would not be separated from each other by a router, so these hosts would also be in the same subnet. However, another PC, connected to the same switch but in a different VLAN, will require its packets to flow through a router to reach Host A, so Host A's IP address would need to be in a different subnet compared to this new host. ### 2. Why does the formula for the number of hosts per subnet (2H -- 2) require the subtraction **of two hosts?** ### a **2.** D. By definition, two address values in every IPv4 subnet cannot be used as host IPv4 addresses: the first (lowest) numeric value in the subnet for the subnet ID and the last (highest) numeric value in the subnet for the subnet broadcast address. ### 3. A Class B network needs to be subnetted such that it supports 100 subnets and 100 **hosts/subnet. Which of the following answers list a workable combination for the number of network, subnet, and host bits? (Choose two answers.)** ### a **3.** B and C. At least 7 subnet bits are needed because 26 = 64, so 6 subnet bits could not number 100 different subnets. Seven subnet bits could because 27 = 128 \>= 100. Similarly, 6 host bits is not enough because 26 -- 2 = 62, but 7 host bits is enough because 27 − 2 = 126 \>= 100. The number of network, subnet, and host bits must total 32 bits, making one of the answers incorrect. The answer with 8 network bits cannot be correct because the question states that a Class B network is used, so the number of network bits must always be 16. The two correct answers have 16 network bits (required because the question states the use of a Class B network) and at least 7 subnet and host bits each. ### 4. Which of the following are private IP networks? (Choose two answers.) ### a **4.** A and C. The private IPv4 networks, defined by RFC 1918, are Class A network 10.0.0.0, the 16 Class B networks from 172.16.0.0 to 172.31.0.0, and the 256 Class C networks that begin with 192.168. ### 5. Which of the following are public IP networks? (Choose three answers.) ### a **5.** A, D, and E. The private IPv4 networks, defined by RFC 1918, are Class A network 10.0.0.0, the 16 Class B networks from 172.16.0.0 to 172.31.0.0, and the 256 Class C networks that begin with 192.168. The three correct answers are from the public IP network range, and none are reserved values. ### 6. Before Class B network 172.16.0.0 is subnetted by a network engineer, what parts of **the structure of the IP addresses in this network already exist, with a specific size? (Choose two answers.)** ### a **6.** A and C. An unsubnetted Class A, B, or C network has two parts: the network and host parts. ### 7. A network engineer spends time thinking about the entire Class B network 172.16.0.0 **and how to subnet that network. He then chooses how to subnet this Class B network and creates an addressing and subnetting plan, on paper, showing his choices. If you compare his thoughts about this network before subnetting the network to his thoughts about this network after mentally subnetting the network, which of the following occurred to the parts of the structure of addresses in this network?** ### A **7.** B. An unsubnetted Class A, B, or C network has two parts: the network and host parts. To perform subnetting, the engineer creates a new subnet part by borrowing host bits, shrinking the number of host bits. The subnet part of the address structure exists only after the engineer chooses a nondefault mask. The network part remains a constant size. ### Chapter 12 **Foundation Topics Section Questions** - Classful Network Concepts 1--5 ### 1. Which of the following are not valid Class A network IDs? (Choose two answers.) ### a **1.** B and C. Class A networks have a first octet in the range of 1--126, inclusive, and their network IDs have a 0 in the last three octets. 130.0.0.0 is actually a Class B network (first octet range 128--191, inclusive). All addresses that begin with 127 are reserved, so 127.0.0.0 is not a Class A network. ### 2. Which of the following are not valid Class B network IDs? ### A **2.** E. All Class B networks begin with values between 128 and 191, inclusive, in their first octets. The network ID has any value in the 128--191 range in the first octet, and any value from 0 to 255 inclusive in the second octet, with decimal 0s in the final two octets. Two of the answers show a 255 in the second octet, which is acceptable. Two of the answers show a 0 in the second octet, which is also acceptable. ### 3. Which of the following are true about IP address 172.16.99.45's IP network? (Choose **two answers.)** ### A **3.** B and D. The first octet (172) is in the range of values for Class B addresses (128--191). As a result, the network ID can be formed by copying the first two octets (172.16) and writing 0s for the last two octets (172.16.0.0). The default mask for all Class B networks is 255.255.0.0, and the number of host bits in all unsubnetted Class B networks is 16. ### 4. Which of the following are true about IP address 192.168.6.7's IP network? (Choose **two answers.)** ### A **4.** A and C. The first octet (192) is in the range of values for Class C addresses (192--223). As a result, the network ID can be formed by copying the first three octets (192.168.6) and writing 0 for the last octet (192.168.6.0). The default mask for all Class C networks is 255.255.255.0, and the number of host bits in all unsubnetted Class C networks is 8. ### 5. Which of the following is a network broadcast address? ### a **5.** D. To find the network broadcast address, first determine the class, and then determine the number of host octets. At that point, convert the host octets to 255 to create the network broadcast address. In this case, 10.1.255.255 is in a Class A network, with the last three octets as host octets, for a network broadcast address of 10.255.255.255. For 192.168.255.1, it is a Class C address, with the last octet as the host part, for a network broadcast address of 192.168.255.255. Address 224.1.1.255 is a Class D address, so it is not in any unicast IP network and the question does not apply. For 172.30.255.255, it is a Class B address, with the last two octets as host octets, so the network broadcast address is 172.30.255.255. ### Chapter 13 **Foundation Topics Section Questions** - Subnet Mask Conversion 1--3 - Defining the Format of IPv4 Addresses 4--7 ### 1. Which of the following answers lists the prefix (CIDR) format equivalent of **255.255.254.0?** ### a **1.** C. If you think about the conversion one octet at a time, the first two octets each convert to 8 binary 1s. 254 converts to 8-bit binary 11111110, and decimal 0 converts to 8-bit binary 00000000. So, the total number of binary 1s (which defines the prefix length) is 8 + 8 + 7 + 0 = /23. ### 2. Which of the following answers lists the prefix (CIDR) format equivalent of **255.255.255.240?** ### a **2.** B. If you think about the conversion one octet at a time, the first three octets each convert to 8 binary 1s. 240 converts to 8-bit binary 11110000, so the total number of binary 1s (which defines the prefix length) is 8 + 8 + 8 + 4 = /28. ### 3. Which of the following answers lists the dotted-decimal notation (DDN) equivalent **of /30?** ### a **3. B.** /30 is the equivalent of the mask that in binary has 30 binary 1s. To convert that to DDN format, write down all the binary 1s (30 in this case), followed by binary 0s for the remainder of the 32-bit mask. Then take 8 bits at a time and convert from binary to decimal (or memorize the nine possible DDN mask octet values and their binary equivalents). Using the /30 mask in this question, the binary mask is 11111111 11111111 11111111 11111100. Each of the first three octets is all binary 1s, so each converts to 255\. The last octet, 11111100, converts to 252, for a DDN mask of 255.255.255.252. See Appendix A, "Numeric Reference Tables," for a decimal/binary conversion table. ### 4. Working at the help desk, you receive a call and learn a user's PC IP address and mask **(10.55.66.77, mask 255.255.255.0). When thinking about this using classful logic, you determine the number of network (N), subnet (S), and host (H) bits. Which of the following is true in this case?** ### a **4. C.** The size of the network part is always either 8, 16, or 24 bits, based on whether it is Class A, B, or C, respectively. As a Class A address, N=8. The mask 255.255.255.0, converted to prefix format, is /24. The number of subnet bits is the difference between the prefix length (24) and N, so S=16 in this case. The size of the host part is a number that, when added to the prefix length (24), gives you 32, so H=8 in this case. ### 5. Working at the help desk, you receive a call and learn a user's PC IP address and mask **(192.168.9.1/27). When thinking about this using classful logic, you determine the number of network (N), subnet (S), and host (H) bits. Which of the following is true in this case?** ### a **5. A.** The size of the network part is always either 8, 16, or 24 bits, based on whether it is Class A, B, or C, respectively. As a Class C address, N=24. The number of subnet bits is the difference between the prefix length (27) and N, so S=3 in this case. The size of the host part is a number that, when added to the prefix length (27), gives you 32, so H=5 in this case. ### 6. Which of the following statements is true about classless IP addressing concepts? ### a 6\. D. Classless addressing rules define a two-part IP address structure: the prefix and the host part. This logic ignores Class A, B, and C rules, and can be applied to the 32-bit IPv4 addresses from any address class. By ignoring Class A, B, and C rules, classless addressing ignores any distinction as to the network part of an IPv4 address. ### 7. Which of the following masks, when used as the only mask within a Class B network, **would supply enough subnet bits to support 100 subnets? (Choose two.)** ### a **7. A and B.** The masks in binary define a number of binary 1s, and the number of binary 1s defines the length of the prefix (network + subnet) part. With a Class B network, the network part is 16 bits. To support 100 subnets, the subnet part must be at least 7 bits long. Six subnet bits would supply only 26 = 64 subnets, while 7 subnet bits supply 27 = 128 subnets. The /24 answer supplies 8 subnet bits, and the 255.255.255.252 answer supplies 14 subnet bits. ### Chapter 14 **Foundation Topics Section Questions** - Defining a Subnet 1 - Analyzing Existing Subnets: Binary 2 - Analyzing Existing Subnets: Decimal 3--6 ### 1. When you think about an IP address using classful addressing rules, an address can have three parts: network, subnet, and host. If you examined all the addresses in one subnet, in binary, which of the following answers correctly states which of the three parts of the addresses will be equal among all addresses? (Choose the best answer.) ### a 1\. D. When using classful IP addressing concepts as described in Chapter 13, "Analyzing Subnet Masks," addresses have three parts: network, subnet, and host. For addresses in a single classful network, the network parts must be identical for the numbers to be in the same network. For addresses in the same subnet, both the network and subnet parts must have identical values. The host part differs when comparing different addresses in the same subnet. ### 2. Which of the following statements are true regarding the binary subnet ID, subnet **broadcast address, and host IP address values in any single subnet? (Choose two answers.)** ### a **2. B and D.** In any subnet, the subnet ID is the smallest number in the range, the subnet broadcast address is the largest number, and the usable IP addresses sit between them. All numbers in a subnet have identical binary values in the prefix part (classless view) and network + subnet part (classful view). To be the lowest number, the subnet ID must have the lowest possible binary value (all 0s) in the host part. To be the largest number, the broadcast address must have the highest possible binary value (all binary 1s) in the host part. The usable addresses do not include the subnet ID and subnet broadcast address, so the addresses in the range of usable IP addresses never have a value of all 0s or 1s in their host parts. ### 3. Which of the following is the resident subnet ID for IP address 10.7.99.133/24? ### a **3. C.** The mask converts to 255.255.255.0. To find the subnet ID, for each octet of the mask that is 255, you can copy the IP address's corresponding values. For mask octets of decimal 0, you can record a 0 in that octet of the subnet ID. As such, copy the 10.7.99 and write a 0 for the fourth octet, for a subnet ID of 10.7.99.0. ### 4. Which of the following is the resident subnet for IP address 192.168.44.97/30? ### a **4.** C. First, the resident subnet (the subnet ID of the subnet in which the address resides) must be numerically smaller than the IP address, which rules out one of the answers. The mask converts to 255.255.255.252. As such, you can copy the first three octets of the IP address because of their value of 255. For the fourth octet, the subnet ID value must be a multiple of 4, because 256 -- 252 (mask) = 4. Those multiples include 96 and 100, and the right choice is the multiple closest to the IP address value in that octet \(97) without going over. So, the correct subnet ID is 192.168.44.96. ### 5. Which of the following is the subnet broadcast address for the subnet in which IP **address 172.31.77.201/27 resides?** ### a **5.** C. The resident subnet ID in this case is 172.31.77.192. You can find the subnet broadcast address based on the subnet ID and mask using several methods. Following the decimal process in the book, the mask converts to 255.255.255.224, making the interesting octet be octet 4, with magic number 256 -- 224 = 32. For the three octets where the mask = 255, copy the subnet ID (172.31.77). For the interesting octet, take the subnet ID value (192), add magic (32), and subtract 1, for 223. That makes the subnet broadcast address 172.31.77.223. ### 6. A fellow engineer tells you to configure the DHCP server to lease the last 100 usable **IP addresses in subnet 10.1.4.0/23. Which of the following IP addresses could be leased as a result of your new configuration?** ### a **6.** C. To answer this question, you need to find the range of addresses in the subnet, which typically then means you need to calculate the subnet ID and subnet broadcast address. With a subnet ID/mask of 10.1.4.0/23, the mask converts to 255.255.254.0. To find the subnet broadcast address, following the decimal process described in this chapter, you can copy the subnet ID's first two octets because the mask's value is 255 in each octet. You write a 255 in the fourth octet because the mask has a 0 on the fourth octet. In octet 3, the interesting octet, add the magic number (2) to the subnet ID's value (4), minus 1, for a value of 2 + 4 -- 1 = 5. (The magic number in this case is calculated as 256 -- 254 = 2.) That makes the broadcast address 10.1.5.255. The last usable address is 1 less: 10.1.5.254. The range that includes the last 100 addresses is 10.1.5.155 -- 10.1.5.254. ### Chapter 15 **Foundation Topics Section Questions** - Installing Cisco Routers 1 - Enabling IPv4 Support on Cisco Routers 2--6 ### 1. Which of the following installation steps are more likely required on a Cisco router, **but not typically required on a Cisco switch? (Choose two answers.)** ### a **1.** B and E. Cisco routers have an on/off switch, but Cisco switches generally do not. ### 2. Which of the following commands might you see associated with a router CLI, but **not with a switch CLI?** ### a **2.** B. Cisco routers that do not also have any Layer 2 switch features support commands needed for Layer 3 routing as well as commands in common between Layer 2 switching and Layer 3 routing devices. In this case, the **show interfaces status** and **show mac** **address-table** commands happen to be commands supported on Layer 2 switches but not on routers. Both types of devices use the **show running-config** command. Of the answers, only the **show ip interface brief** command is unique to routers. ### 3. Which answers list a task that could be helpful in making a router interface G0/0 ready **to route packets? (Choose two answers.)** ### a **3.** A and C. To route packets on an interface, the router interface configuration must include an IP address and mask. One correct command shows the correct single command used to configure both values, while one incorrect command shows those settings as two separate commands. Also, to route packets, the interface must reach an "up/up" state; that is, the **show interfaces** and other commands list two status values, and both must be "up." The **no shutdown** command enables the interface. ### **4.** The output of the show ip interface brief command on R1 lists interface status codes **of "down" and "down" for interface GigabitEthernet 0/0. The interface connects to a LAN switch with a UTP straight-through cable. Which of the following could be true?** ### A **4.** C. If the first of the two status codes is "down," it typically means that a Layer 1 problem exists. In this case, the question states that the router connects to a switch with a UTP straight-through cable, which is the correct cable pinout. Of the two answers that mention the **shutdown** command, if the router interface were shut down, the first router status code would be "administratively down," so that answer is incorrect. However, if the neighboring device interface sits in a shutdown state, the router will sense no electrical signals over the cable, seeing that as a physical problem, and place the interface into a "down/down" state, making that answer correct. Second, the two answers that mention interface IP addresses have no impact on the status codes of the **show interfaces brief** command. Both answers imply that the interface does not have an IP address configured. However, both the first and second status codes are not related to whether IP addresses have been configured or not, making both answers incorrect. ### 5. Which of the following commands do not list the IP address and mask of at least one **interface? (Choose two answers.)** ### a **5.** C and E. The **show ip interface brief** command lists all the interface IPv4 addresses but none of the masks. The **show version** command lists none of the IP addresses and none of the masks. The other three commands list both the address and mask. ### 6. Which of the following is different on the Cisco switch CLI for a Layer 2 switch as compared with the Cisco router CLI? ### a **6.** B. A router has one IPv4 address for each interface in use, whereas a LAN switch has a single IPv4 address that is just used for accessing the switch. The rest of the answers list configuration settings that use the same conventions on both routers and switches. ### Chapter 16 **Foundation Topics Section Questions** - IP Routing 1 - Configuring Connected Routes 2 - Configuring Static Routes 3--5 - IP Forwarding with the Longest Prefix Match 6 ### 1. Router R1 lists a route in its routing table. Which of the following answers list a fact **from a route that the router uses when matching the packet's destination address? (Choose two answers.)** ### a **1.** A and C. The route defines the group of addresses represented by the route using the subnet ID and mask. The router can use those numbers to find the range of addresses that should be matched by this route. The other two answers list facts useful when forwarding packets that happen to match the route. ### 2. After configuring a working router interface with IP address/mask 10.1.1.100/26, which **of the following routes would you expect to see in the output of the show ip route command? (Choose two answers.)** ### a **2.** A and D. First, for the subnetting math, address 10.1.1.100, with mask /26, implies a subnet ID of 10.1.1.64. Also, mask /26 converts to a DDN mask of 255.255.255.192. For any working router interface, after adding the **ip address** command to configure an address and mask, the router adds a connected route for the subnet. In this case, that means the router adds a connected route for subnet 10.1.1.64 255.255.255.192. The router also adds a route called a local route, which is a route for the interface IP address with a 255.255.255.255 mask. In this case, that means the router adds a local route for address 10.1.1.100 with mask 255.255.255.255. ### 3. An engineer configures a static IPv4 route on Router R1. Which of the following **pieces of information should not be listed as a parameter in the configuration command that creates this static IPv4 route?** ### a **3.** C. The **ip route** command can refer to the IP address of the next-hop router or to the local router's interface. It also refers to the subnet ID and matching subnet mask, defining the range of addresses matched by the route. ### 4. Which of the following commands correctly configures a static route? ### a **4.** A. The correct syntax lists a subnet number, then a subnet mask in dotted-decimal form, and then either an outgoing interface or a next-hop IP address. ### 5. A network engineer configures the ip route 10.1.1.0 255.255.255.0 s0/0/0 command **on a router and then issues a show ip route command from enable mode. No routes for subnet 10.1.1.0/24 appear in the output. Which of the following could be true?** ### A **5.** B. The **ip route** command can reference an outgoing interface or a next-hop IP address, and the command lists a next-hop IP address, which rules out one answer. The command does use the correct syntax, ruling out another answer. There is no requirement for a router to have any particular interface IP addresses in relation to the configuration of an **ip route** command, ruling out yet another answer. The checks that IOS uses when looking at a new **ip route** command include whether the outgoing interface is up/up, whether the next-hop address is reachable, and, if there is a competing route from another source, whether the other route has a better administrative distance. ### 6. A router lists the following partial output from the show ip route command. Out **which interface will the router route packets destined to IP address 10.1.15.122?** 10.0.0.0/8 is variably subnetted, 8 subnets, 5 masks O 10.1.15.100/32 \[110/50\] via 172.16.25.2, 00:00:04, GigabitEthernet0/0/0 O 10.1.15.64/26 \[110/100\] via 172.16.25.129, 00:00:09, GigabitEthernet0/1/0 O 10.1.14.0/23 \[110/65\] via 172.16.24.2, 00:00:04, GigabitEthernet0/2/0 O 10.1.15.96/27 \[110/65\] via 172.16.24.129, 00:00:09, GigabitEthernet0/3/0 O 0.0.0.0/0 \[110/129\] via 172.16.25.129, 00:00:09, GigabitEthernet0/0/0 ### a **6.** D. Destination address 10.1.15.122 matches all the routes listed except the host route to 10.1.15.100/32. In that case, the router will choose the matching route that has the longest prefix length, that is, the prefix-style mask with the highest number. In this case, that route lists subnet 10.1.15.96 and mask /27, which lists interface G0/3/0 as the outgoing interface. ### Chapter 17 **Foundation Topics Section Questions** - VLAN Routing with Router 802.1Q Trunks 1, 2 - VLAN Routing with Layer 3 Switch SVIs 3, 4 - VLAN Routing with Layer 3 Switch Routed Ports 5, 6 ### 1. Router 1 has a Fast Ethernet interface 0/0 with IP address 10.1.1.1. The interface is connected **to a switch. This connection is then migrated to use 802.1Q trunking. Which of the following commands could be part of a valid configuration for Router 1's Fa0/0 interface? (Choose two answers.)** **f. encapsulation dot1q 4** ### a **1.** A and F. Of all the commands listed, only the two correct answers are syntactically correct router configuration commands. The command to enable 802.1Q trunking is **encapsulation dot1q** *vlan\_id*. ### 2. Router R1 has a router-on-a-stick (ROAS) configuration with two subinterfaces of **interface G0/1: G0/1.1 and G0/1.2. Physical interface G0/1 is currently in a down/down state. The network engineer then configures a shutdown command when in interface configuration mode for G0/1.1 and a no shutdown command when in interface configuration mode for G0/1.2. Which answers are correct about the interface state for the subinterfaces? (Choose two answers.)** ### A **2.** B and C. Subinterface G0/1.1 must be in an administratively down state due to the **shutdown** command being issued on that subinterface. For subinterface G0/1.2, its status cannot be administratively down because of the **no shutdown** command. G0/1.2's state will then track to the state of the underlying physical interface. With a physical interface state of down/down, subinterface G0/1.2 will be in a down/down state in this case. ### 3. A Layer 3 switch has been configured to route IP packets between VLANs 1, 2, and 3 **using SVIs, which connect to subnets 172.20.1.0/25, 172.20.2.0/25, and 172.20.3.0/25, respectively. The engineer issues a show ip route connected command on the Layer 3 switch, listing the connected routes. Which of the following answers lists a piece of information that should be in at least one of the routes?** ### a **3.** C. The configuration of the Layer 3 switch's routing feature uses VLAN interfaces. The VLAN interface numbers must match the associated VLAN ID, so with VLANs 1, 2, and 3 in use, the switch will configure **interface vlan 1**, **interface vlan 2** (which is the correct answer), and **interface vlan 3**. The matching connected routes, like all connected IP routes, will list the VLAN interfaces. As for the incorrect answers, a list of connected routes will not list any next-hop IP addresses. Each route will list an outgoing interface; the outgoing interface will not be a physical interface, but rather a VLAN interface, because the question states that the configuration uses SVIs. Finally, all the listed subnets have a /25 mask, which is 255.255.255.128, so none of the routes will list a 255.255.255.0 mask. ### 4. An engineer has successfully configured a Layer 3 switch with SVIs for VLANs 2 and **3. Hosts in the subnets using VLANs 2 and 3 can ping each other with the Layer 3 switch routing the packets. The next week, the network engineer receives a call that those same users can no longer ping each other. If the problem is with the Layer 3 switching function, which of the following could have caused the problem? (Choose two answers.)** ### a **4.** C and D. First, for the correct answers, a Layer 3 switch will not route packets on a VLAN interface unless it is in an up/up state. A VLAN interface will only be up/up if the matching VLAN (with the same VLAN number) exists on the switch. If VTP deletes the VLAN, then the VLAN interface moves to a down/down state, and routing in/out that interface stops. Also, disabling VLAN 2 with the **shutdown** command in VLAN configuration mode also causes the matching VLAN 2 interface to fail, which makes routing on interface VLAN 2 stop as well. As for the incorrect answers, a Layer 3 switch needs only one access port or trunk port forwarding for a VLAN to enable routing for that VLAN, so nine of the ten access ports in VLAN 2 could fail, leaving one working port, and the switch would keep routing for VLAN 2. A **shutdown** of VLAN 4 has no effect on routing for VLAN interfaces 2 and 3. Had that answer listed VLANs 2 or 3, it would definitely be a reason to make routing fail for that VLAN interface. ### 5. A LAN design uses a Layer 3 EtherChannel between two switches SW1 and SW2, **with port-channel interface 1 used on both switches. SW1 uses ports G0/1, G0/2, and G0/3 in the channel. Which of the following are true about SW1's configuration to make the channel be able to route IPv4 packets correctly? (Choose two answers.)** ### A **5.** A and C. With a Layer 3 EtherChannel, the physical ports and the port-channel interface must disable the behavior of acting like a switch port, and therefore act like a routed port, through the configuration of the **no switchport** interface subcommand. (The **routedport** command is not an IOS command.) Once created, the physical interfaces should not have an IP address configured. The port-channel interface (the interface representing the EtherChannel) should be configured with the IP address. ### 6. A LAN design uses a Layer 3 EtherChannel between two switches SW1 and SW2, **with port-channel interface 1 used on both switches. SW1 uses ports G0/1 and G0/2 in the channel. However, only interface G0/1 is bundled into the channel and working. Think about the configuration settings on port G0/2 that could have existed before adding G0/2 to the EtherChannel. Which answers identify a setting that could prevent IOS from adding G0/2 to the Layer 3 EtherChannel? (Choose two answers.)** ### a **6.** B and C. With a Layer 3 EtherChannel, two configuration settings must be the same on all the physical ports, specifically the speed and duplex as set with the **speed** and **duplex** commands. Additionally, the physical ports and port-channel port must all have the **no switchport** command configured to make each act as a routed port. So, having a different speed setting, or being configured with **switchport** rather than **no switchport**, would prevent IOS from adding interface G0/2 to the Layer 3 EtherChannel. As for the wrong answers, both have to do with Layer 2 configuration settings. Once Layer 2 operations have been disabled because of the **no switchport** command, those settings related to Layer 2 that could cause problems on Layer 2 EtherChannels do not then cause problems for the Layer 3 EtherChannel. So, Layer 2 settings about access VLANs, trunking allowed lists, and STP settings, which must match before an interface can be added to a Layer 2 EtherChannel, do not matter for a Layer 3 EtherChannel. ### Chapter 19 **Foundation Topics Section Questions** - Comparing Dynamic Routing Protocol Features 1--3 - OSPF Concepts and Operation 4, 5 - OSPF Areas and LSAs 6 ### 1. Which of the following routing protocols is considered to use link-state logic? ### a **1.** D. Both versions of RIP use distance vector logic, and EIGRP uses a different kind of logic, characterized either as advanced distance vector or a balanced hybrid. ### 2. Which of the following routing protocols use a metric that is, by default, at least partially **affected by link bandwidth? (Choose two answers.)** ### a **2.** C and D. Both versions of RIP use the same hop-count metric, neither of which is affected by link bandwidth. EIGRP's metric, by default, is calculated based on bandwidth and delay. OSPF's metric is a sum of outgoing interfaces costs, with those costs (by default) based on interface bandwidth. ### 3. Which of the following interior routing protocols support VLSM? (Choose three **answers.)** ### a **3.** B, C, and D. Of the listed routing protocols, only the old RIP Version 1 (RIP-1) protocol does not support variable-length subnet masks (VLSM). ### 4. Two routers using OSPFv2 have become neighbors and exchanged all LSAs. As a **result, Router R1 now lists some OSPF-learned routes in its routing table. Which of the following best describes how R1 uses those recently learned LSAs to choose which IP routes to add to its IP routing table?** ### A **4.** C. LSAs contain topology information that is useful in calculating routes, but the LSAs do not directly list the route that a router should add to its routing table. In this case, R1 would run a calculation called the Shortest Path First (SPF) algorithm, against the LSAs, to determine what IP routes to add to the IP routing table. ### 5. Which of the following OSPF neighbor states is expected when the exchange of topology **information is complete between two OSPF neighbors?** ### a **5.** B. Neighboring OSPF routers that complete the database exchange are considered fully adjacent and rest in a full neighbor state. The up/up and final states are not OSPF states at all. The 2-way state is either an interim state or a stable state between some routers on the same VLAN. ### 6. A company has a small/medium-sized network with 15 routers and 40 subnets and **uses OSPFv2. Which of the following is considered an advantage of using a single-area design as opposed to a multiarea design?** ### A **6.** C. The correct answer is the one advantage of using a single-area design. The three wrong answers are advantages of using a multiarea design, with all reasons being much more important with a larger internetwork. ### Chapter 20 **Foundation Topics Section Questions** - Implementing Single-Area OSPFv2 1--3 - OSPFv2 Interface Configuration 4 - Additional OSPFv2 Features 5, 6 ### 1. Which of the following network commands, following the command router ospf **1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?** ### a **1.** B. The **network 10.0.0.0 0.255.255.255 area 0** command works because it matches all interfaces whose first octet is 10. The rest of the commands match as follows: all addresses that end with 0.0.0 (wildcard mask 255.0.0.0); all addresses that begin with 10.0.0 (wildcard mask 0.0.0.255); and all addresses that begin with 10.0 (wildcard mask 0.0.255.255). ### 2. Which of the following network commands, following the command router ospf **1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?** ### a **2.** A. The **network 10.1.0.0 0.0.255.255 area 0** command matches all IP addresses that begin with 10.1, enabling OSPF in area 0 on all interfaces. The answer with wildcard mask 0.255.255.0 is illegal because it represents more than one string of binary 0s separated by binary 1s. The answer with x's is syntactically incorrect. The answer with wildcard mask 255.0.0.0 means "Match all addresses whose last three octets are 0.0.0," so none of the three interfaces are matched. ### 3. Which of the following commands list the OSPF neighbors off interface serial 0/0? **(Choose two answers.)** ### a **3.** A and E. Of the three wrong answers, two are real commands that simply do not list the OSPF neighbors. **show ip ospf interface brief** lists interfaces on which OSPF is enabled but does not list neighbors. **show ip interface** lists IPv4 details about interfaces, but none related to OSPF. One incorrect answer, **show ip neighbor**, is not a valid IOS command. ### 4. An engineer migrates from a more traditional OSPFv2 configuration that uses network **commands in OSPF configuration mode to instead use OSPFv2 interface configuration. Which of the following commands configures the area number assigned to an interface in this new configuration?** ### a **4.** B. With OSPFv2 interface configuration mode, the configuration looks just like the traditional configuration, with a couple of exceptions. The **network** router subcommand is no longer required. Instead, each interface on which OSPF should be enabled is configured with an **ip ospf** *process-id* **area** *area-id* interface subcommand. This command refers to the OSPF routing process that should be enabled on the interface and specifies the OSPFv2 area. ### 5. Which of the following configuration settings on a router does not influence which **IPv4 route a router chooses to add to its IPv4 routing table when using OSPFv2?** ### a **5.** B. SPF calculates the cost of a route as the sum of the OSPF interface costs for all outgoing interfaces in the route. The interface cost can be set directly (**ip ospf cost**), or IOS uses a default based on the reference bandwidth and the interface bandwidth. Of the listed answers, **delay** is the only setting that does not influence OSPFv2 metric calculations. ### 6. OSPF interface configuration uses the ip ospf *process-id* area *area-number* configuration **command. In which modes do you configure the following settings when using this command?** ### A **6.** A and D. The configuration enables OSPF and identifies the area number to use with the interface using an interface subcommand in interface mode: the **ip ospf** *process-id* **area** *area-number* command. However, to explicitly configure the router ID, the configuration must use the **router-id** *router-id-value* command, which is a command issued in OSPF router mode. ### Chapter 21 **Foundation Topics Section Questions** - Implementing Single-Area OSPFv2 1--3 - OSPFv2 Interface Configuration 4 - Additional OSPFv2 Features 5, 6 ### 1. Which of the following network commands, following the command router ospf **1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?** ### a **1.** B and D. By default, IOS assigns Ethernet interfaces an OSPF network type of broadcast, with an OSPF interface priority of 1. As a result, both routers attempt to discover the other routers on the link (which identifies one correct answer). The broadcast network type means that the routers also attempt to elect a DR and BDR. With a tie-in priority, the routers choose the DR based on the highest router ID (RID) values, meaning that R2 will become the DR and R1 will become the BDR. These facts combine to show why the two incorrect answers are incorrect. The other correct answer is correct because the **show ip ospf neighbor** command lists the local router's neighbor relationship state (FULL) and the role filled by that neighbor (DR), which would be the output shown on R1 when R2 is acting as DR. ### 2. Which of the following network commands, following the command router ospf **1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?** ### a **2.** B and C. First, the OSPF point-to-point network type causes the two routers to dynamically discover neighbors, making one answer correct. Next, IOS assigns a default OSPF interface priority of 1, so R1's configured priority of 11 would be better in a DR/BDR election. However, the point-to-point network type causes the router to not use a DR/BDR on the interface. As a result, the answer about R1 becoming the DR is incorrect (because no DR exists at all), and the answer listing a state of "FULL/DR" is incorrect for the same reason. However, the answer that claims that R2 will be neither DR nor BDR is true because no DR or BDR is elected. ### 3. Which of the following commands list the OSPF neighbors off interface serial 0/0? **(Choose two answers.)** ### a **3.** D. The **show ip ospf interface brief** command lists a pair of counters under the heading "Nbrs F/C" on the far right of the output. The first of the two numbers represents the number of fully adjacent neighbors (2 in this case), and the second number represents the total number of neighbors. ### 4. An engineer migrates from a more traditional OSPFv2 configuration that uses network **commands in OSPF configuration mode to instead use OSPFv2 interface configuration. Which of the following commands configures the area number assigned to an interface in this new configuration?** ### a **4.** A and D. As worded, the correct answers list a scenario that would prevent the neighbor relationship. One correct answer mentions the use of two different OSPF areas on the potential OSPF neighbors; to become neighbors, the two routers must use the same area number. The other correct answer mentions the use of two different Hello timers, a mismatch that causes two routers to reject each other and to not become neighbors. The two incorrect answers list scenarios that do not cause issues, making them incorrect answers. One mentions mismatched OSPF process IDs; OSPF process IDs do not need to match for two routers to become neighbors. The other incorrect answer (that is, a scenario that does not cause a problem) mentions the use of two different priority values. The priority values give OSPF a means to prefer one router over the other when electing a DR/BDR, so the setting is intended to be set to different values on different routers and does not cause a problem. ### 5. Which of the following configuration settings on a router does not influence which **IPv4 route a router chooses to add to its IPv4 routing table when using OSPFv2?** ### a **5.** C. As worded, the correct answers should be a scenario that would prevent the neighbor relationship. The answers all list values that are identical or similar on the two routers. Of those, the use of an identical OSPF router ID (RID) on the two routers prevents them from becoming neighbors, making that one answer correct. Of the incorrect answers, both routers must have the same Dead interval, so both using a Dead interval of 40 causes no issues. The two routers can use any OSPF process ID (the same or different value, it does not matter), making that answer incorrect. Finally, the two routers' IP addresses must be in the same subnet, so again that scenario does not prevent R13 and R14 from becoming neighbors. ### 6. OSPF interface configuration uses the ip ospf *process-id* area *area-number* configuration **command. In which modes do you configure the following settings when using this command?** ### A **6.** D. The OSPF **shutdown** command tells the OSPF process to stop operating. That process includes removing any OSPF-learned routes from the IP routing table, clearing the router's LSDB, and closing existing OSPF neighbor relationships. In effect, it causes OSPF to stop working on the router, but it does retain the configuration so that a **no** **shutdown** command will cause the router to start using OSPF again with no changes to the configuration. ### ### Chapter 22 **Foundation Topics Section Questions** - Introduction to IPv6 1--2 - IPv6 Addressing Formats and Conventions 3--6 ### 1. Which of the following was a short-term solution to the IPv4 address exhaustion **problem?** ### a **1.** C. NAT, specifically the PAT feature that allows many hosts to use private IPv4 addresses while being supported by a single public IPv4 address, was one short-term solution to the IPv4 address exhaustion problem. IP version 5 existed briefly as an experimental protocol and had nothing to do with IPv4 address exhaustion. IPv6 directly addresses the IPv4 address exhaustion problem, but it is a long-term solution. ARP has no impact on the number of IPv4 addresses used. ### 2. A router receives an Ethernet frame that holds an IPv6 packet. The router then makes a **decision to route the packet out a serial link. Which of the following statements is true about how a router forwards an IPv6 packet?** ### A **2.** A. Routers use the same process steps when routing IPv6 packets as they do when routing IPv4 packets. Routers route IPv6 packets based on the IPv6 addresses, listed inside the IPv6 header in the IPv6 packets, by comparing the destination IPv6 address to the router's IPv6 routing table. As a result, the router discards the incoming frame's data-link header and trailer, leaving an IPv6 packet. The router compares the destination (not source) IPv6 address in the header to the router's IPv6 (not IPv4) routing table and then forwards the packet based on the matched route. ### 3. Which of the following is the shortest valid abbreviation for FE80:0000:0000:0100:0000:0000:0000:0123? ### a **3.** D. If you are following the steps in the book, the first step removes up to three leading 0s in each quartet, leaving FE80:0:0:100:0:0:0:123. This leaves two strings of consecutive all-0 quartets; by changing the longest string of all 0s to ::, the address is FE80:0:0:100::123. ### 4. Which of the following is the shortest valid abbreviation for 2000:0300:0040:0005:6000:0700:0080:0009? ### a **4.** B. This question has many quartets that make it easy to make a common mistake: removing trailing 0s in a quartet of hex digits. To abbreviate IPv6 addresses, only leading 0s in a quartet should be removed. Many of the quartets have trailing 0s (0s on the right side of the quartet), so make sure to not remove those 0s. ### 5. Which of the following is the unabbreviated version of IPv6 address 2001:DB8::200:28? ### a **5.** A. The unabbreviated version of an IPv6 address must have 32 digits, and only one answer has 32 hex digits. In this case, the original number shows four quartets and a ::. So, the :: was replaced with four quartets of 0000, making the number have eight quartets. Then, for each quartet with fewer than four digits, leading 0s were added so that each quartet has four hex digits. ### 6. Which of the following is the prefix for address 2000:0000:0000:0005:6000:0700:0080:0009, assuming a mask of /64? ### a **6.** C. The /64 prefix length means that the last 64 bits, or last 16 digits, of the address should be changed to all 0s. That process leaves the unabbreviated prefix as 2000:0000:0000:0005:0000:0000:0000:0000. The last four quartets are all 0s, making that string of all 0s be the longest and best string of 0s to replace with ::. After removing the leading 0s in other quartets, the answer is 2000:0:0:5::/64. ### Chapter 23 **Foundation Topics Section Questions** - Global Unicast Addressing Concepts 1--4 - Unique Local Unicast Addresses 5 ### 1. Which of the following IPv6 addresses appears to be a unique local unicast address, based on its first few hex digits? ### a **1.** C. Unique local addresses begin with FD in the first two digits. ### 2. Which of the following IPv6 addresses appears to be a global unicast address, based on its first few hex digits? ### a **2.** A. Global unicast addresses can begin with many different initial values, but most commonly begin with either a hex 2 or 3. ### 3. When subnetting an IPv6 address block, an engineer shows a drawing that breaks **the address structure into three pieces. Comparing this concept to a three-part IPv4 address structure, which part of the IPv6 address structure is most like the IPv4 network part of the address?** **e. Subnet router anycast** ### a **3.** D. The global routing prefix is the address block, represented as a prefix value and prefix length, given to an organization by some numbering authority. All IPv6 addresses inside the company have the same value in these initial bits of their IPv6 addresses. Similarly, when a company uses a public IPv4 address block, all the addresses have the same value in the network part. ### 4. When subnetting an IPv6 address block, an engineer shows a drawing that breaks **the address structure into three pieces. Assuming that all subnets use the same prefix length, which of the following answers lists the name of the field on the far right side of the address?** **e. Subnet router anycast** ### a **4.** B. Subnetting a global unicast address block, using a single prefix length for all subnets, breaks the addresses into three parts. The parts are the global routing prefix, subnet, and interface ID. ### 5. For the IPv6 address FD00:1234:5678:9ABC:DEF1:2345:6789:ABCD, which part of the address is considered the global ID of the unique local address? ### a **5.** D. Unique local addresses begin with a 2-hex-digit prefix of FD, followed by the 10-hex-digit global ID. ### Chapter 24 **Foundation Topics Section Questions** - Implementing Unicast IPv6 Addresses on Routers 1--3 - Special Addresses Used by Routers 4--5 ### 1. Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 0200.0001.000A. Which of the following commands, added in R1's Gigabit Ethernet 0/1 configuration mode, gives this router's G0/1 interface a unicast IPv6 address of 2001:1:1:1:1:200:1:A, with a /64 prefix length? ### A **1.** A. The one correct answer lists the exact same IPv6 address listed in the question, with a /64 prefix length and no spaces in the syntax of the answer. Another (incorrect) answer is identical, except that it leaves a space between the address and prefix length, which is incorrect syntax. The two answers that list the **eui-64** parameter list an address and not a prefix; they should list a prefix to be correct, although neither would have resulted in the IPv6 address listed in the question. ### 2. Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 5055.4444.3333. This interface has been configured with the ipv6 address 2000:1:1:1::/64 eui-64 subcommand. What unicast address will this interface use? ### a **2.** B. With the **eui-64** parameter, the router will calculate the interface ID portion of the IPv6 address based on its MAC address. Beginning with 5055.4444.3333, the router injects FF FE in the middle (5055.44FF.FE44.3333). Then the router inverts the seventh bit in the first byte. Mentally, this converts hex 50 to binary 01010000, changing bit 7 so that the string is 0101 0010 and converting back to hex 52. The final interface ID value is 5255:44FF:FE44:3333. The wrong answers simply list a different value. ### 3. Router R1 currently supports IPv4, routing packets in and out all its interfaces. R1's configuration needs to be migrated to support dual-stack operation, routing both IPv4 and IPv6. Which of the following tasks must be performed before the router can also support routing IPv6 packets? (Choose two answers.) ### A **3.** A and C. Of the four answers, the two correct answers show the minimal required configuration to support IPv6 on a Cisco router: enabling IPv6 routing (**ipv6** **unicast-routing**) and enabling IPv6 on each interface, typically by adding a unicast address to each interface (**ipv6 address...**). The two incorrect answers list nonexistent commands. ### 4. Router R1 has an interface named Gigabit Ethernet 0/1, whose MAC address has been set to 0200.0001.000A. The interface is then configured with the ipv6 address 2001:1:1:1:200:FF:FE01:B/64 interface subcommand; no other ipv6 address commands are configured on the interface. Which of the following answers lists the linklocal address used on the interface? ### a **4.** A. With an **ipv6 address** command configured for a global unicast address, but without a link-local address configured with an **ipv6 address** command, the router calculates its link-local address on the interface based on its MAC address and EUI-64 rules. The first half of the link-local address begins FE80:0000:0000:0000. The router then calculates the second half of the link-local address value by taking the MAC address (0200.0001.000A), injecting FF FE in the middle (0200.00FF.FE01.000A), and flipping the seventh bit (0000.00FF.FE01.000A). ### 5. Which of the following multicast addresses is defined as the address for sending packets to only the IPv6 routers on the local link? ### a **5.** B. FF02::1 is used by all IPv6 hosts on the link, FF02::5 is used by all OSPFv3 routers, and FF02::A is used by all EIGRPv6 routers. FF02::2 is used to send packets to all IPv6 routers on a link. ### Chapter 25 **Foundation Topics Section Questions** - Connected and Local IPv6 Routes 1--2 - Static IPv6 Routes 3--6 - The Neighbor Discovery Protocol 7--8 ### 1. A router has been configured with the ipv6 address 2000:1:2:3::1/64 command on its G0/1 interface as shown in the figure. The router creates a link-local address of FE80::FF:FE00:1 as well. The interface is working. Which of the following routes will the router add to its IPv6 routing table? (Choose two answers.) ### a **1.** A and C. With an IPv6 address on a working interface, the router adds a connected route for the prefix (subnet) implied by the **ipv6 address** command. It also adds a local host route (with a /128 prefix length) based on the unicast address. The router does not add a route based on the link-local address. ### 2. A router has been configured with the ipv6 address 3111:1:1:1::1/64 command on its **G0/1 interface and ipv6 address 3222:2:2:2::1/64 on its G0/2 interface. Both interfaces are working. Which of the following routes would you expect to see in the output of the show ipv6 route connected command? (Choose two answers.)** ### a **2.** A and C. The two correct answers show the correct subnet ID (prefix) and prefix length for the two connected subnets: 3111:1:1:1::/64 and 3222:2:2:2::/64. The answer with the /128 prefix length is shown in a local route, but those routes are not displayed by the **show ipv6 route connected** command. The other incorrect answer lists the entire IPv6 address with a /64 prefix length, and the entire address would not be displayed as a prefix when using a /64 prefix. ### 3. An engineer needs to add a static IPv6 route for prefix 2000:1:2:3::/64 to Router R5's **configuration, in the figure shown with question 1. Which of the following answers shows a valid static IPv6 route for that subnet, on Router R5?** ### a **3. A.** All four answers show examples of commands that use an outgoing interface. The two commands that begin with **ip route** define only IPv4 routes; the commands would be rejected because of the IPv6 prefixes listed in the commands. The two commands that begin with **ipv6 route** are syntactically correct, but the command should list the local router's interface (an interface on the router on which the command is being configured). R5 needs to use its local S0/1/1 interface as the outgoing interface. ### 4. An engineer needs to add a static IPv6 route for prefix 2000:1:2:3::/64 to Router R5 in **the figure shown with question 1. Which of the following answers shows a valid static IPv6 route for that subnet on Router R5?** ### a **4.** B. All four answers show examples of commands that use a next-hop router IPv6 address. Two of the answers list R5's own IPv6 address (unicast or link-local), which is incorrect; the answer should be an address on the neighboring router, R6 in this case. For the two answers that list addresses on Router R6, the one that lists R6's global unicast address is correct. The one that lists R6's link-local address would also require R5's outgoing interface, so the answer that lists FE80::FF:FE00:6 would be rejected as well. ### 5. An engineer types the command ipv6 route 2001:DB8:8:8::/64 2001:DB8:9:9::9 129 **in configuration mode of Router R1 and presses Enter. Later, a show ipv6 route command does not list any route for subnet 2001:DB8:8:8::/64. Which of the following could have caused the route to not be in the IPv6 routing table?** ### A **5.** C. IOS will add a new static route to the IPv6 routing table if, when using a next-hop global unicast address, the router has a working route to reach that next-hop address and there is no better (lower administrative distance) route for the exact same subnet. So, the correct answer identifies one reason why the route would not appear. The answer that mentions a better route with administrative distance of 110 is a valid reason for the static route to not appear, but the question states that no route for the subnet appears in the routing table, so clearly that competing route does not exist. The other two answers are incorrect about the **ipv6 route** command. This command can use a link-local next-hop address but does not have to do so. Also, when using a global unicast address as next-hop, the command does not also require an outgoing interface parameter. ### 6. The command output shows two routes from the longer output of the show ipv6 **route command. Which answers are true about the output? (Choose two answers.)** R1\# show ipv6 route static ! Legend omitted for brevity S 2001:DB8:2:2::/64 \[1/0\] via 2001:DB8:4:4::4 S ::/0 \[1/0\] via Serial0/0/1, directly connected ### A **6.** A and B. The output shows two static routes, as noted with the "S" code on the far left. Both were added to the IPv6 routing table because of **ipv6 route** commands. Both have an administrative distance of 1, which is listed as the first number in brackets. For the two incorrect answers, note that the **ipv6 address** interface subcommand does cause IOS to add connected IPv6 routes to the routing table, and the phrase "directly connected" with one route might make you think this is a connected route. However, the "S" in the far left identifies the source of the route. Likewise, the answer that mentions an IPv6 routing protocol is incorrect because both routes have a code of S, meaning static. ### 7. PC1, PC2, and Router R1 all connect to the same VLAN and IPv6 subnet. PC1 wants to send its first IPv6 packet to PC2. What protocol or message will PC1 use to discover the MAC address to which PC1 should send the Ethernet frame that encapsulates this IPv6 packet? ### a **7.** B. PC1 needs to discover PC2's MAC address. Unlike IPv4, IPv6 does not use ARP, instead using NDP. Specifically, PC1 uses the NDP Neighbor Solicitation (NS) message to request that PC2 send back an NDP Neighbor Advertisement (NA). SLAAC relates to address assignment, and not to discovering a neighbor's MAC address. ### 8. Which of the following pieces of information does a router supply in an NDP Router Advertisement (RA) message? (Choose two answers.) ### a **8.** A and C. The NDP RA lists the router IPv6 address, the IPv6 prefixes known on the link, and the matching prefix lengths. When using DHCPv6, the host learns the IPv6 address of the DNS server through DHCPv6 messages. For MAC addresses of on-link neighbors, hosts use NDP NS and NA messages. ### Chapter 26 **Foundation Topics Section Questions** - Comparing Wired and Wireless Networks 1 - Wireless LAN Topologies 2--4 - Other Wireless Topologies 5--6 - Wireless Bands and Channels 7--8 ### **1.** Wired Ethernet and Wi-Fi are based on which two IEEE standards, respectively? ### a **1.** C. The IEEE 802.3 standard defines Ethernet, while 802.11 defines Wi-Fi. ### **2.** Devices using a wireless LAN must operate in which one of the following modes? ### a **2.** B. WLANs require half-duplex operation because all stations must contend for use of a channel to transmit frames. ### **3.** An access point is set up to offer wireless coverage in an office. Which one of the following is the correct 802.11 term for the resulting standalone network? ### a **3.** C. An AP offers a basic service set (BSS). BSA is incorrect because it is a Basic Service Area, or the cell footprint of a BSS. BSD is incorrect because it does not pertain to wireless at all. IBSS is incorrect because it is an Independent BSS, or an ad hoc network, where an AP

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