Chapter 9: Multiarea OSPF Quiz
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Questions and Answers

What does the access-class command do when configured in line configuration mode?

  • It displays statistics for VTY access attempts.
  • It defines which IPs are allowed remote access to the router EXEC process. (correct)
  • It allows all IP addresses remote access to the router.
  • It restricts administrative access to routers.

    • Why is it important to verify the ACL configuration used to secure VTY ports?

  • To check the performance statistics of the router.
  • To confirm that the VTY ports are correctly secured against unauthorized access. (correct)
  • To ensure that all IP addresses are allowed access.
  • To display the output of the SSH attempts.

    • What command can be used to clear the access-list counters?

  • remove access-list stats
  • clear access-list counters (correct)
  • reset access list
  • clear access-list

    • Which of the following statements is true regarding the incoming and outgoing connections restricted by the access-class command?

    <p>It can restrict both incoming and outgoing connections based on an access list.</p> Signup and view all the answers

    What is one main purpose of restricting VTY access on Cisco devices?

    <p>To prevent unauthorized remote access to the router.</p> Signup and view all the answers

    Which command is used to display the results after SSH attempts to connect to devices?

    <p>show access-lists</p> Signup and view all the answers

    What does the restriction of VTY access help to achieve?

    <p>Improved security by controlling access.</p> Signup and view all the answers

    How are the addresses restricted by the access-class command determined?

    <p>By specifying IP addresses in an access list.</p> Signup and view all the answers

    What is the primary purpose of an Access Control List (ACL)?

    <p>To control whether a router forwards or drops packets</p> Signup and view all the answers

    What is the role of a router designated as an ABR in an OSPF implementation?

    <p>It connects different areas within OSPF.</p> Signup and view all the answers

    What happens if an ACL has no permit statements?

    <p>All traffic will be explicitly denied</p> Signup and view all the answers

    Which layer of the OSI model can packet filtering occur according to ACLs?

    <p>Layer 3 or Layer 4</p> Signup and view all the answers

    Which command would be used to view OSPFv2 neighbor relationships?

    <p>show ip ospf neighbor</p> Signup and view all the answers

    How do ACLs typically manage network traffic flow?

    <p>By comparing packets to each Access Control Entry in sequential order</p> Signup and view all the answers

    How can a router become an ABR in OSPFv3?

    <p>By having multiple interfaces in different areas.</p> Signup and view all the answers

    What is a characteristic of the last statement in an ACL?

    <p>It is always an implicit deny</p> Signup and view all the answers

    Which command provides a summary of OSPFv2-enabled interfaces and their costs?

    <p>show ip ospf interface brief</p> Signup and view all the answers

    Which type of network traffic can ACLs help filter?

    <p>Traffic based on services like FTP or HTTP</p> Signup and view all the answers

    What does the 'IA' notation in the output of the 'show ip route ospf' command signify?

    <p>Inter-area route</p> Signup and view all the answers

    In OSPFv2, what information is included when using the 'show ip ospf' command?

    <p>Routing protocols configured and number of areas</p> Signup and view all the answers

    What happens to packets originating from the router itself regarding ACLs?

    <p>They are bypassed for dropping or forwarding rules</p> Signup and view all the answers

    What is an Access Control Entry (ACE) in the context of ACLs?

    <p>A permit or deny statement within an ACL</p> Signup and view all the answers

    What is NOT a valid command for verifying multiarea OSPFv2 settings?

    <p>show ip route summary</p> Signup and view all the answers

    Which statement is true about special commands for multiarea OSPF implementation?

    <p>OSPF does not require special commands for multiarea configuration.</p> Signup and view all the answers

    What is the purpose of the hashing function applied to host statements in an ACL?

    <p>To optimize the search for a host ACL entry</p> Signup and view all the answers

    How does a router process packets when an ACL is configured on an inbound interface?

    <p>It strips off frame information before checking the ACL</p> Signup and view all the answers

    Which of the following is NOT a common error related to Standard IPv4 ACLs?

    <p>Entering ACEs in the correct sequence</p> Signup and view all the answers

    What happens if a packet matches an ACL statement?

    <p>The packet can be either permitted or denied</p> Signup and view all the answers

    What is a potential outcome if an ACL denies access incorrectly?

    <p>Important services will become unavailable to legitimate users</p> Signup and view all the answers

    What should be taken into consideration when applying an ACL to an interface?

    <p>The direction and interface type</p> Signup and view all the answers

    What may happen if PC2 is intended to be denied access to a server, but the ACL denies access for PC1 as well?

    <p>ACL rules must be re-evaluated for accuracy</p> Signup and view all the answers

    What does the 'show access-list' command indicate when a deny statement is present?

    <p>Specific traffic is being blocked</p> Signup and view all the answers

    What does the command 'access-list 101 deny tcp any any' match?

    <p>Any IP packet that has a TCP header</p> Signup and view all the answers

    Which of the following access-list commands blocks packets from a specific host with an IP address of 1.1.1.1 to 2.2.2.2?

    <p>access-list 101 deny ip host 1.1.1.1 2.2.2.2</p> Signup and view all the answers

    Which command would deny all UDP packets from the subnet 1.1.1.0/24 to any destination?

    <p>access-list 101 deny udp 1.1.1.0 0.0.0.255 any</p> Signup and view all the answers

    What is the function of the command 'access-list 101 deny tcp any gt 49151 host 10.1.1.1 eq 23'?

    <p>Blocks TCP packets from source port greater than 49151 to a specific host</p> Signup and view all the answers

    Which of the following is NOT a well-known port number for a TCP application?

    <p>8080 (RTP)</p> Signup and view all the answers

    Which protocol is associated with the port number 69?

    <p>TFTP</p> Signup and view all the answers

    What does the option 'deny icmp any any' achieve?

    <p>Blocks all ICMP packets regardless of their source or destination</p> Signup and view all the answers

    In an extended access-list, what does 'eq 23' signify?

    <p>Indicates an exact match to the port number 23</p> Signup and view all the answers

    Which access-list command would you use to permit HTTP traffic?

    <p>access-list 101 permit tcp any eq 80</p> Signup and view all the answers

    What is the significance of using a named access control list?

    <p>They allow for more intuitive identification and management</p> Signup and view all the answers

    Which command can be used to match any TCP packet from any source to the host with IP address 10.1.1.1 on port 23?

    <p>access-list 101 deny tcp any host 10.1.1.1 eq 23</p> Signup and view all the answers

    What is the purpose of using the 'telnet' keyword in an access-list instead of specifying port 23?

    <p>It simplifies the command by using a keyword.</p> Signup and view all the answers

    In an access-list, the command 'access-list 101 deny udp 1.0.0.0 0.255.255.255 lt 1023 any' primarily targets which type of packets?

    <p>UDP packets from any source using a port lower than 1023.</p> Signup and view all the answers

    What range of numbers should be used for defining an extended access-list?

    <p>100 to 199 or 2000 to 2699</p> Signup and view all the answers

    Which command correctly logs extended access-list traffic?

    <p>access-list <number> log</p> Signup and view all the answers

    What should be included in an access-list to match all hosts in the subnet 172.16.4.0/25?

    <p>access-list permit tcp 172.16.4.0 0.0.0.127 any</p> Signup and view all the answers

    Which access-list command denies traffic from IP address 192.168.7.200/26 to any host in the subnet 192.168.7.14/29?

    <p>access-list deny icmp 192.168.7.200 0.0.0.63 192.168.7.14 0.0.0.7</p> Signup and view all the answers

    How would you construct an access-list entry to permit traffic from the web server at 10.2.3.4/23 to clients in the subnet of host 10.4.5.6/22?

    <p>access-list permit tcp 10.2.3.4 0.0.1.255 10.4.5.0 0.0.3.255</p> Signup and view all the answers

    Study Notes

    Chapter 9: Multiarea OSPF

    • Multiarea OSPF is used in small to medium-sized business networks to improve efficiency and scalability.
    • Using areas allows OSPF to handle a larger link-state database (LSDB) more efficiently, reducing processing and memory overhead.
    • Multiarea OSPFv2 and OSPFv3 are implemented in a two-layer area hierarchy.
    • The backbone area is area 0, and all other areas connect to it.
    • Internal routers have all interfaces in the same area.
    • Backbone routers are located in area 0 and connect other areas.
    • Area border routers (ABRs) have interfaces in multiple areas.
    • Autonomous system border routers (ASBRs) have interfaces on one external network.
    • OSPF Link State Advertisements (LSAs) provide network details needed for efficient operation.

    OSPF LSA Types

    • LSAs are database records that describe network details.
    • LSAs, in combination, describe the entire OSPF network topology.
    • The first five LSAs are always supported in implementations of Multiarea OSPF.
    • LSA Type 1: Routers advertise their directly connected OSPF-enabled links and are flooded within the area.
    • LSA Type 2: Used on non-broadcast and multi-access networks, provide information about the DR on the multiaccess segment.
    • LSA Type 3: ABRs use these LSAs to advertise networks from other areas.
    • LSA Type 4: Identifies ASBRs and routes to it, generated by ABRs when ASBRs exist in the area.
    • LSA Type 5: Used to advertise external (non-OSPF) networks and are flooded throughout the routing domain. 

    OSPF Routing Table

    • OSPF routes in an IPv4 routing table are identified by "O" (intra-area).
    • Interarea routes are identified as "O IA".
    • External routes are identified by "O E1" (external type 1) or "O E2" (external type 2).

    OSPF Route Calculation

    • Routers prioritize calculating optimal routes within their area first (Type 1 and Type 2 LSAs).
    • Then they calculate routes to other areas (Type 3 LSAs).
    • Finally, they calculate routes to external autonomous systems (Type 5 LSAs).

    Configuring Multiarea OSPF

    • Gather network requirements and parameters.
    • Define OSPF parameters (single-area vs. multiarea, IP addressing plan, OSPF areas, network topology).
    • Configure the multiarea OSPF implementation.
    • Verify the configuration.

    Configuring Multiarea OSPFv2

    • There are no special commands required.
    • A router becomes an Area Border Router (ABR) when it has interfaces in two or more different areas

    Configuring Multiarea OSPFv3

    • There are no special commands required.
    • A router becomes an Area Border Router (ABR) when it has interfaces in two or more different areas

    Verifying Multiarea OSPFv2

    • Use commands like show ip ospf neighbor, show ip ospf, show ip ospf interface, show ip ospf interface brief, show ip route ospf, show ip ospf database to verify the OSPFv2 operation.

    Verifying Multiarea OSPFv3

    • Use commands show ipv6 protocols, show ipv6 interface brief, show ipv6 route ospf, show ipv6 ospf database to verify the OSPFv3 operation.

    Chapter 7: Access Control Lists

    • Access Control Lists (ACLs) determine whether a router forwards or drops packets based on information in the packet header.
    • ACLs are used to limit traffic, increase network performance, and provide network security, but aren't configured by default.
    • Standard IPv4 ACLs filter traffic based on source IP addresses; Extended IPv4 ACLs filter traffic based on source and destination IP addresses and ports, as well as other fields.

    ACL Operation

    • ACLs in routers help control what traffic is allowed to pass.
    • ACLs filter traffic as it approaches or leaves a specific interface.
    • Inbound ACLs act on traffic entering an interface before it is processed.
    • Outbound ACLs act on traffic exiting interface after it has been processed.

    Wildcard Masks

    • Wildcard masks are used to define a match in ACLs, allowing for more flexibility than literal address matching.
    • A wildcard mask consists of binary digits; where 1 means ignore the corresponding bit, and 0 means to match the value of the bit.
    • Wildcard masks are often abbreviated using keywords like "host" or "any".

    ACL Configurations

    • Standard ACL use only source IP addresses and are positioned near the destination.
    • Extended ACL statements use protocol, source IP, source port, destination IP, and destination port information and are positioned close to the source.
    • ACLS need testing before deployment and attention must be paid to the configuration and use order of entries.

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    Related Documents

    CCNA Routing and Switching - Chapter 9: Multiarea OSPF PDF

    Description

    Test your knowledge on Multiarea OSPF with this quiz based on Chapter 9. Discover the importance of area hierarchy, LSAs, and router types such as ABRs and ASBRs. Enhance your understanding of how OSPF improves network efficiency and scalability.

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