Basic Device Configuration

Module 1 - Basic Device Configuration

• Show ipv6 interface brief: Displays a summary of all IPv6-enabled interfaces on a router, including the IPv6 address and operational status.
• C Code: Identifies directly connected routes in the routing table.
• Link Local: Required address type for an IPv6-enabled interface.
• Show interface: Displays packet flow counts, collisions, and buffer failures on an interface.
• Pipe (|): Enables filtering of commands.
• Begin: An expression that shows all output lines starting from the line matching the filter expression.
• The command history feature can accomplish setting the command history buffer size and recalling previously entered commands.
• For Cisco Catalyst switches, a blinking green LED indicates normal system operation, while an amber LED indicates the system is receiving power but not functioning properly.
• A crossover Ethernet cable is used to connect one switch to another when neither switch supports the auto-MDIX feature.
• SSH offers encryption, providing security for remote connections by encrypting all transmitted data, unlike Telnet, which uses plaintext communications.
• To bring the line protocol up for VLAN 99 after configuring it as the management VLAN, connect a host to an interface associated with VLAN 99.
• A default SVI is created for VLAN 1 for switch administration.
• "Switch:" prompt is displayed when a network administrator successfully accesses the boot loader on a switch to recover from a system crash.
• Router bootup sequence: Perform POST and load the bootstrap program, locate and load the Cisco IOS software, and locate and load the startup configuration file or enter setup mode.
• The first action in the boot sequence when a switch is powered on is loading a power-on self-test program.
• An administrator needs physical access to the router to reset a lost password on a router.
• When configuring a switch for SSH access, the "username username secret secret" command is required with the login local command.
• The "show interfaces" command provides information about the status of all interfaces, including giants, runts, and collisions.

Module 2 - Switching Concepts

• A host with a 1 Gbps NIC connecting to a Cisco Catalyst 2960 switch with a 100 Mbps port will autonegotiate to 100 Mbps.
• Routers separate broadcast domains.
• LAN switches alleviate network congestion using fast port speeds and fast internal switching.
• Switches add the source MAC address, if it is not already, and sends unicast frames to specific ports.
• Adding a switch to a network increases the size of the broadcast domain.
• A Layer 2 switch determines which interface to use to forward a frame based on the destination MAC address.
• A switch creates many smaller collision domains, whereas a hub increases the size of a single collision domain.
• Cisco LAN switches forward frames out all ports except the receiving port if the destination MAC address is not in the MAC address table.
• Frame buffering helps alleviate network congestion when a 10 Gbps port forwards data to a 1 Gbps port.
• Store-and-forward switching makes use of the FCS value.
• "Port density" represents the number of available ports for an Ethernet switch.
• Switches use the source MAC address and the incoming port to keep the MAC address table information current.
• Full duplex communication allows both ends to transmit and receive simultaneously.
• Full duplex increases the effective bandwidth.
• Switches use the source MAC address to build the MAC address table.
• Store-and-forward switching ensures that the frame is free of physical and data-link errors.
• Routers can serve as a boundary to divide a Layer 2 broadcast domain.
• Frame buffers on a switch hold traffic, alleviating network congestion.
• Switches eliminate collisions on an Ethernet network.

Module 3 - VLANs

• VLANs improve network performance by segmenting broadcast domains.
• VLANs improve security by isolating sensitive data from the rest of the network.
• It is not best practice to configure the native VLAN as VLAN 1.
• Native VLANs are assigned to 802.1Q trunk ports to carry untagged traffic.
• All switch ports are assigned to VLAN 1 by default.
• The native and management VLANs are VLAN 1 by default.
• VLAN 1 cannot be renamed or deleted.
• Based on the exhibit, PC1 will receive the ARP broadcast frame from PC4 because PC1 and PC4 are in the same VLAN, VLAN 10 and broadcasts are contained within a VLAN
• Based on the exhibit, PC2, PC3 and PC6 will receive the ARP broadcast frame due to being in the same VLAN and broadcasts are contained within a VLAN.
• Based on the exhibit, PC5 will receive the ARP broadcast frame from PC3 due to being in the same VLAN and broadcasts are contained within a VLAN.
• DTP is a Cisco proprietary protocol for switchport trunk auto-negotiation.
• Two switchports on a link both configured as dynamic auto will not successfully negotiate a trunk.
• The default switchport mode for Cisco Catalyst switches is dynamic auto.
• TRUNK and DYNAMIC DESIRABLE DTP modes will form a trunk with an interface that is configured as dynamic auto
• When an administrator deletes VLAN 10 from the switch, ports associated with it become inactive.
• VLAN configurations of normal range VLANs are stored in flash memory on a Catalyst switch.
• Switches from other vendors do not fully support DTP, which is a probable cause for trunking failures between Cisco switches and other vendors’ switches.
• The vlan.dat file on a switch holds the VLAN database.
• A separate VLAN should be used to carry uncommon untagged frames to avoid bandwidth contention on data VLANs.
• When a Cisco switch receives untagged frames on a 802.1Q trunk port, the traffic is switched to Native VLAN ID by default.
• Two types of point-to-point connections utilize VLAN trunking: between two switches that utilize multiple VLANs, and between a switch and a server that has an 802.1Q NIC.
• SECURITY, COST REDUCTION, and Improved IT Staff efficiency are three primary benefits of using VLANs.
• On a Cisco switch, extended range VLAN information is stored in the running configuration file.
• Normal range VLANs are stored in Flash memory on a Cisco switch by default.
• An administrator accesses and configures a switch via the management VLAN.
• The "show interfaces trunk" command is used to view the native VLAN on a switch.
• The vlan.dat file is stored in flash memory.
• A separate VLAN is needed for voice traffic when an organization includes Cisco IP phones in its network to ensure voice quality.
• The command "switchport trunk allowed vlan 30" on Fa0/5 allows only VLAN 30 on Fa0/5 if the switch currently allows traffic tagged with VLANs 10 and 20 across trunk port Fa0/5.

Chapter 4 - Inter-VLAN

• Scenario A is a Layer 3 inter-VLAN solution.
• Scenario B is a legacy inter-VLAN solution.
• Scenario C is a router-on-a-stick inter-VLAN solution.
• The command to verify the subinterfaces are in the routing table: show ip route
• The command to check the list of VLANs and their assigned ports: show vlan
• The command to verify the status of an access port and its access mode VLAN: show interfaces interface-id switchport
• The command to verify the status and IP address of all interfaces in a condensed format: show ip interface brief
• A multilayer switch with routing enabled provides the highest bandwidth at Layer 3 and also provide a default gateway for the PC to access a web server on another network.
• Routing traffic internally to a Layer 3 switch device is required to provide inter-VLAN routing on a switched network with more than 1000 VLANs.
• When configuring a router as part of a router-on-a-stick inter-VLAN routing topology, the IP address should be assigned to the subinterface.
• A router with at least two LAN interfaces should be used for legacy inter-VLAN routing.
• Multilayer switches are more expensive than router-on-a-stick implementations, which is a disadvantage of using multilayer switches for inter-VLAN routing.
• Router on a stick inter-VLAN inter-VLAN communication design requires multiple subinterfaces .
• Using router-on-a-stick inter-VLAN routing does not scale well beyond 50 VLANs
• The number represents VLAN ID for the "encapsulation dot1Q 10 native router subinterface command".
• The no switchport command creates a routed port for a single network while configuring inter-VLAN routing on a multilayer switch
• The commands "Switch(config)# interface gigabitethernet 0/1, Switch(config-if)# no switchport" will make this port a routed port.
• The operational mode should be TRUNK on a switch port to connect it to a router for router-on-a-stick inter-VLAN routing.
• An SVI is needed for each VLAN when describing the SVI inter-VLAN routing method.
• Traffic is routed via internal VLAN interfaces on a multilayer switch.
• The router that is configured with multiple subinterfaces is required to perform router-on-a-stick inter-VLAN routing.
• Show ip interface and show running-config can be used in the router to identify the problem.

Chapter 5 - STP Concepts

• STP is a Layer 2 loop prevention protocol for Ethernet LANs.
• Unknown unicast, multicast and broadcast frames could cause loops within an Ethernet LAN.
• The device elected by Spanning Tree Algorithm: root bridge.
• By default the following determines the root bridge: the MAC address of the switch.
• Root bridge switch: THE LOWEST BRIDGE ID.
• The port closest to the root bridge in terms of least overall cost is the ROOT PORT.
• The port on the segment that has the lowest path cost to the root bridge is the DESIGNATED PORT.
• The ports that will forward Ethernet frames: DESIGNATED and ROOT PORT
• Individual port costs along the path from the switch to the root bridge : ROOT PATH COST
• Switched send BPDU’s every 2nd second
• BPDU - Bridge protocol Data unis
• The STP port states that are merged into the RSTP discarding port state: DISABLED, BLOCKING and LISTENING
• Protocol that was designed to bring faster convergence to STP: RSTP
• Technology to solve the problem of a device being unable to get an IPv4 from a DHCP server with STP forwarding delay timers: PORT FAST
• State for configured PortFast ports: FORWARDING
• The way switches find the best paths to the root bridge: Each switch will analyze the sum of all port costs to reach the root and use the path with the lowest cost.
• Cisco Catalyst default STP operation mode: PVST+
• The MAC address determines the root bridge with connected trunk links and default STP configurations.
• The first step of the spanning-tree election process( when all switches are implemented under Spanning Tree Protocol: All the switches send out BPDUs advertising themselves as the root bridge.
• The two concepts related to a switch port that is intended to have only end devices attached: EDGE PORT and PORT FAST
• Used states by Rapid PVST+: DISCARDING, LEARNING and FORWARDING
• Listenting port state under PVST running, can participate in BPDU by receiving BPDUs, but does not forward data frames
• The port role when there is not other port to lower cost to the root bridge: ROOT PORT
• Describing a switch port in configuring: The switch port immediately transitions from blocking to the forwarding state, and The switch port should never receive BPDUs.
• Correcting spanning tree failure: manually remove redudant links in the switched network.
• The additonal information contained in the 12-bit extended system ID, as part of the BPDU is the VLAN ID
• Verifying if it is a root bridge, use SHOW SPANNING-TREE command.
• This is the decription of redundancy, ensure no single point of failure by designing the network for multiple path between switches

MODULE 7 - DCHP

• The message sent by a DHCPv4 client to initiate the lease obtaining process: DHCPDISCOVER
• The two DHCPv4 messages sent by the server, in the lease are DHCPV4 and DHCPOFFER.
• DHCPv4 used in the lease renewal are DHCPV4 and DHCPREQUEST
• The two steps when the DHCP-enabled client PC uses broadcast message with a DHCP server: DHCPDISCOVER and DHCPREQUEST
• The administrator is configuring router to obtain IP parameters from a DHCPv4 server
• The DHCPReques Message is a broadcast during address lease so it could decline other offers.
• The four IPV4 addresses in DHCPDCOVER, destination, client, default gateway, subnet.
• Message sent requesting IP address: DHCPDISCOVER
• Message sent as DHCP expires: DHCPREQUEST
• This is the Destination IPv4 address: 255.255.255.255
• if the DHCP server is available in the local messages are (Discover, offer, request, acknowledegement)
• the most likely scenario on DHCP client to be assigned in a dynamic IP address from ISP is through SOHO or home broadband router.
• dynamic allocation is the method that assigns IPV4 addresses for lease

MODULE 8 - SLAAC

• Reason for the DHCPREQUEST Message during DHCPV4 process: Notify subnets of leased IP addresses
• How the DHCPDISCOVER is transmitted: The address is sent with broadcast address as destination address.
• Client uses this IPv4 when it's requesting initial packet: 255.255.255.255
• Circumstances on why Routers are configured as DHCPv4 client: Router intended for SOHO or an ISP Requirement
• DHCP Message target address: Clients hardware address.
• Which address type is automatically created by default on a host interface when no RAs are
• Link-local address
• Best method to describe stateless DHCP: SLAAC with stateless DHCPV6
• Two ICMPv6 messages that are used in SLAAC ( Router Solicitiation, Router Advertisements)
• Command to a router to enable the ipv6 all routers multicast: ipv6 unicast-routing
• Flag setttings : A=1 M=0, O=0
• Message sent by the host: Router Solicitation(RS) -Method to used by Host with IPV6: DAD -The Port UDP with send DHCPV6: 547 What DHCPV6 message : SOLICIT
  • What DHCPV6 if : REQUEST

Module 9 - DHCPV6

• The command used to display active link and local IP address for client, show ipv6 dhcp binding
• For the DHCP relay agent on the agent : ipv6 dhcp relay destination When client ensures client has unique configured address, will send ICMPv6 and target the ipv6 address. Method using ipv6 enable host: router advertisments. The two methods used for interface ID : EUI-64 , RANDOM GENERATION. When clients are using SLAAC: it will need to solicit ICMPv6. Command is needed to the interface a dchpv6 client: ipv6 addres dhcp

The client receives the IPv6 to use the stateful DCHPv6 for the obtainment: The Icmpv6 Router Advertisment

The IPv6 address destination is used to locate the DHCPv6 - FF02 : 1.2

The best alternative for DYnamically the Dynamic to ipv6 for information. SLAAC with Stateless

DHCPv6 message to the server which message does it send DHCPv6 INFORMATION-REQUEST

The process to do this in for the unique with the process: DAD

What are characters SLAAC- the Link local and DYnamically the ICPv6 addresses.

What the O flag set and one the Client should Automatically and the DCHPv6

The Statement the config- the to send IPv6 RA.