CCNA 3 Chapter 8 v6 Exam Answers

What is used to create the OSPF neighbor table?

Which command will verify that a router that is running OSPFv3 has formed an adjacency with other routers in its OSPF area?

The show ipv6 ospf neighbor command will verify neighbor adjacencies for OSPFv3 routers. The other options do not provide neighbor information.

When a network engineer is configuring OSPFv3 on a router, which command would the engineer issue immediately before configuring the router ID?

The OSPFv3 router ID is configured in the IPv6 router configuration mode. The clear ipv6 ospf process privileged EXEC command forces OSPF on the router to renegotiate neighbor adjacencies. The interface serial 0/0/1 command causes the router to enter interface configuration mode where OSPFv3 is enabled by issuing the ipv6 ospf process-id area area-id command.

Fill in the blank.
OSPF uses ___ as a metric.

The OSPF metric is cost. The lowest cost path to a remote destination is the preferred path and is installed in the routing table.

What will an OSPF router prefer to use first as a router ID?

The first preference for an OSPF router ID is an explicitly configured 32-bit address. This address is not included in the routing table and is not defined by the network command. If a router ID that is configured through the router-id command is not available, OSPF routers next use the highest IP address available on a loopback interface, as loopbacks used as router IDs are also not routable addresses. Lacking either of these alternatives, an OSPF router will use the highest IP address from its active physical interfaces.

Which command should be used to check the OSPF process ID, the router ID, networks the router is advertising, the neighbors the router is receiving updates from, and the default administrative distance?

The show ip ospf neighbor command is used to verify that the router has formed an adjacency with its neighboring routers. The show ip ospf command displays the OSPF process ID and router ID, the OSPF area information, as well as the last time the SPF algorithm was calculated. The show ip ospf interface command provides detailed information about every OSPF-enabled interface.

Open the PT Activity. Perform the tasks in the activity instructions and then answer the question. R1 and R2 could not establish an EIGRP adjacency. What is the problem?​

Which OSPF component is identical in all routers in an OSPF area after convergence?

Each OSPF router views the network differently as the root of a unique SPF tree. Each router builds adjacencies based on its own position in the topology. Each routing table in the area is developed individually through the application of the SPF algorithm. The link-state database for an area, however, must reflect the same information for all routers.

By default, what is the OSPF cost for any link with a bandwidth of 100 Mb/s or greater?

OSPF uses the formula: Cost = 100,000,000 / bandwidth. Because OSPF will only use integers as cost, any bandwidth of 100 Mb/s or greater will all equal a cost of 1.

Which command will provide information specific to OSPFv3 routes in the routing table?

The show ipv6 route ospf command gives specific information that is related to OSPFv3 routes in the routing table. The show ipv6 route command will show the entire routing table. The show ip route and show ip route ospf commands are used with OSPFv2.


Single area OSPFv3 has been enabled on a router via the ipv6 router ospf 20 command. Which command will enable this OSPFv3 process on an interface of that router?

The command to enable an OSPFv3 process on a router interface is ipv6 ospf process-id area area-id. In the case the process ID is 20 and the area ID is 0.

What happens immediately after two OSPF routers have exchanged hello packets and have formed a neighbor adjacency?

During the exchange of hello packets, OSPF routers negotiate the election process and set the OSPF parameters. DBD packets are exchanged after that step has been completed. DBD packets contain abbreviated lists of link-state information. After that information has been exchanged, OSPF routers exchange Type 3 LSR packets to request further information.

By order of precedence, match the selection of router ID for an OSPF-enable router to the possible router ID options. (Not all option are used.)

Cisco routers determine the OSPF router ID based on the preferential order of configured router ID, IPv4 addresses of loopback interfaces, and IPv4 addresses of active physical interfaces.

Which OPSF packet contains the different types of link-state advertisements?

Link-state update (LSU) packets contain different types of link-state advertisements (LSAs). The LSUs are used to reply to link-state requests (LSRs) and to announce new information.

Fill in the blank.The election of a DR and a BDR takes place on ___ networks, such as Ethernet networks.

There is no need to have a DR/BDR election on a point-to-point link.

Match each OSPF packet type to how it is used by a router. (Not all options are used.)

What does a Cisco router use automatically to create link-local addresses on serial interfaces when OSPFv3 is implemented?

Since serial interfaces do not have MAC addresses, OSPFv3 automatically assigns a link-local address to them derived from the first available MAC address from the pool of Ethernet interface addresses on the router. A FE80::/10 prefix is added. The router then applies the EUI-64 process to the MAC address by inserting FFFE into the middle of the existing 48-bit address and flipping the seventh bit.

What are two reasons that will prevent two routers from forming an OSPFv2 adjacency? (Choose two.)

There may be several reasons why two routers running OSPF will fail to form an OSPF adjacency, including these:
The subnet masks do not match, causing the routers to be on separate networks.
OSPF Hello or Dead Timers do not match.
OSPF network types do not match.
There is a missing or incorrect OSPF network command.
Mismatched IOS versions, the use of private IP addresses, and different types of interface ports used on a switch are not causes for an OSPF adjacency failing to form between two routers.

A network administrator enters the command ipv6 router ospf 64 in global configuration mode. What is the result of this command?

The basic command to implement OSPFv3 on a router uses the same process-id parameter as OSPFv2 to assign a locally-significant number to the OSPF process. OSPF does not use autonomous system numbers. Following the assignment of the process ID, a prompt will direct the user to manually assign a router ID. After the router ID is assigned, the reference bandwidth can be set.

What are the two purposes of an OSPF router ID? (Choose two.)

OSPF router ID does not contribute to SPF algorithm calculations, nor does it facilitate the transition of the OSPF neighbor state to Full. Although the router ID is contained within OSPF messages when router adjacencies are being established, it has no bearing on the actual convergence process.


Match the information to the command that is used to obtain the information. (Not all options are used.)

Match the OSPF state with the order in which it occurs. (Not all options are used.)

Which three addresses could be used as the destination address for OSPFv3 messages? (Choose three.)

OSPFv6 messages can be sent to either the OSPF router multicast FF02::5, the OSPF DR/BDR multicast FF02::6, or the link-local address.