CCNA 3 v6 Chapter 6: Check Your Understanding Questions Answers

CCNA 3 v6.0 (Scaling Networks v6) Chapter 6: EIGRP: Check Your Understanding Questions Answers

1. What is the purpose of using protocol-dependent modules in EIGRP?

  • To accommodate routing of different network layer protocols
  • To describe different routing processes
  • To identify different application layer protocols
  • To use different transport protocols for different packets

Explanation: EIGRP is designed to route several network layer protocols by using PDMs. For example, EIGRP can be used to route IPv4 and IPv6, as well as other network layer protocols. There are separate instances of PDM for different network layer protocols.

2. If all router Ethernet interfaces in an EIGRP network are configured with the default EIGRP timers, how long will a router wait by default to receive an EIGRP packet from its neighbor before declaring the neighbor unreachable?

  • 5 seconds
  • 10 seconds
  • 15 seconds
  • 30 seconds

Explanation: EIGRP uses the hold time as the maximum time it should wait for receiving a hello packet (or other EIGRP packets) from its neighbor before declaring that the neighbor is unreachable. By default the hold time is three times greater than the hello interval. On LAN interfaces, the default hello time is 5 seconds, and the default hold time is 15 seconds.

3. Which two EIGRP packet types are sent with unreliable delivery? (Choose two.)

  • Acknowledgment packet
  • Hello packet
  • Query packet
  • Reply packet
  • Update packet

Explanation: The Update, Query, and Reply EIGRP packet types require reliable delivery.

4. Which destination MAC address is used when a multicast EIGRP packet is encapsulated into an Ethernet frame?

  • 01-00-5E-00-00-09
  • 01-00-5E-00-00-10
  • 01-00-5E-00-00-0A
  • 01-00-5E-00-00-0B

Explanation: When an EIGRP multicast packet is encapsulated into an Ethernet frame, the destination MAC address is 01-00-5E-00-00-0A.

5. What is identified within the opcode of an EIGRP packet header?

  • The EIGRP autonomous system metrics
  • The EIGRP hold timer agreed upon with a neighbor
  • The EIGRP message type that is being sent to or received from a neighbor
  • The EIGRP sum of delays from source to destination

Explanation: The EIGRP packet header opcode is used to identify the EIGRP packet type: Update (1), Query (3), Reply (4), and Hello (5).

6. Why would a network administrator use a wildcard mask in the network command when configuring a router to use EIGRP?

  • To exclude some interfaces from the EIGRP process
  • To reduce the router overhead
  • To send a manual summarization
  • To subnet at the time of the configuration

Explanation: The wildcard mask in the EIGRP network command is used to define precisely which network or subnets participate in the EIGRP process. Only interfaces that have addresses in a subnet included in a network command will participate in EIGRP.

7. An administrator issues the router eigrp 100 command on a router. What is the number 100 used for?

  • As the autonomous system number
  • As the length of time this router will wait to hear Hello packets from a neighbor
  • As the maximum bandwidth of the fastest interface on the router
  • As the number of neighbors supported by this router

Explanation: The router eigrp 100 command uses the number as a process ID to keep track of the running instance of the EIGRP process, as several EIGRP processes can be run at the same time. This number is called the autonomous system number.

8. What information does EIGRP maintain within the routing table?

  • Adjacent neighbors
  • All routes known to the router
  • Both successors and feasible successors
  • Only feasible successors
  • Only successors

Explanation: Only successor routes are offered to the routing table.

9. Which table does EIGRP use to store all routes that are learned from EIGRP neighbors?

  • The adjacency table
  • The neighbor table
  • The routing table
  • The topology table

Explanation: An EIGRP router maintains a topology table that includes entries for every destination that the router learns from directly connected EIGRP neighbors.

10. Which command is used to display the bandwidth of an interface on an EIGRP-enabled router?

  • show ip route
  • show interfaces
  • show ip interface brief
  • show ip protocols

Explanation: The privileged EXEC mode command show interfaces is used to verify the default or configured bandwidth value on an interface. Correct bandwidth values are important for efficient routing with EIGRP.

11. A new network administrator has been asked to verify the metrics that are used by EIGRP on a Cisco device. Which two EIGRP metrics are measured by using static values on a Cisco device? (Choose two.)

  • Bandwidth
  • Delay
  • Load
  • MTU
  • Reliability

Explanation: Bandwidth and delay are static values that are not actually tracked by a device. Load and reliability are tracked dynamically by a device over a default period of time. MTU is not used for EIGRP metrics.

12. How do EIGRP routers establish and maintain neighbor adjacencies?

  • By comparing known routes to information received in updates
  • By dynamically learning new routes from neighbors
  • By exchanging Hello packets with neighboring routers
  • By exchanging neighbor tables with directly attached routers
  • By exchanging routing tables with directly attached routers

Explanation: EIGRP routers use Hello packets to establish and maintain adjacencies.

13. What is indicated when an EIGRP route is in the passive state?

  • The route has the highest path cost of all routes to that destination network.
  • The route is a feasible successor and will be used if the active route fails.
  • The route is viable and can be used to forward traffic.
  • The route must be confirmed by neighboring routers before it is put in the active state.
  • There is no activity on the route to that network.

Explanation: Passive state means that the router topology table is stable and is converged.

14. What is the multicast address used by an EIGRP-enabled router operating with IPv6?

  • FF02::1
  • FF02::A
  • FF02::B

Explanation: The multicast address for EIGRP for IPv6 is FF02::A, which is the shortened form of FF02:0000:0000:0000:0000:0000:0000:A

15. Which configuration is necessary to ensure successful operation of EIGRP for IPv6?

  • The eigrp router-id command requires an IPv6 address in the router configuration mode.
  • The network command is required in the router configuration mode.
  • The no shutdown command is required in the router configuration mode.
  • The router eigrp autonomous-system command is required in the router configuration mode.

Explanation: By default, the EIGRP for IPv6 process is in a shutdown state. The EIGRP for IPv6 process must be activated by using the no shutdown command in router configuration mode.

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