Chapter 10: Quiz - Troubleshooting OSPFv3 (Answers) CCNPv8 ENARSI

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

show running-configuration
show ipv6 ospf neighbor
show ipv6 route ospf
show ipv6 interface brief

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

2. Refer to the exhibit. Which would be chosen as the router ID of R2?

2001:DB8:CAFE:2::/64
LLA: FE80::2
2001:DB8:CAFE:A001::/64
The router ID has to be manually configured.

Explanation: OSPFv3 requires a 32-bit router ID to be assigned before OSPF can be enabled on an interface.This can be manually configured or derived from an IPv4 address configured on the loopback or active interface on the router. In this case the only configured interfaces have 128 bit IPv6 addresses so the router ID has to be manually configured.

3. A network engineer is troubleshooting a single-area OSPFv3 implementation across routers R1, R2, and R3. During the verification of the implementation, it is noted that the routing tables on R1 and R2 do not include the entry for a remote LAN on R3. Examination of R3 shows the following:

that all interfaces have correct addressing
that the routing process has been globally configured
that correct router adjacencies have formed

What additional action taken on R3 could solve the problem?

Enable the OSPFv3 routing process on the interface connected to the remote LAN.
Use the network command to configure the LAN network under the global routing process.
Force DR/BDR elections to occur where required.
Restart the OPSFv3 routing process.

Explanation: Once it is configured globally, OSPFv3 has to be enabled on each participating IPv6 interface via the ipv6 ospf*process-id area area-id* command. The network command is not used in OPSFv3. Because all other aspects of OSPFv3 are confirmed as working correctly, forcing DR/BDR elections and restarting the OSPFv3 process are unlikely to resolve one missing route entry.

4. An administrator is troubleshooting OSPFv3 adjacency issues. Which command would the administrator use to confirm that OSPFv3 hello and dead intervals are matching between routers?

show ipv6 ospf interface
show ipv6 ospf
show ipv6 protocols
show ipv6 ospf neighbor

Explanation: The show ipv6 ospf interface command can be used by an administrator to verify key interface specific OSPFv3 configuration settings, including the hello and dead intervals.

5. An administrator is troubleshooting an OSPFv3 network and wants to view the PID, the RID, the reference bandwidth, and the area parameters for both IPv4 and IPv6 address families. Which single command can be used to display the information?

show ip protocols
show ospfv3
show ipv6 ospf database
show ipv6 ospf

Explanation: The command show ospfv3 will display general OSPFv3 parameters for IPv4 and IPv6 address families, including the PID, the RID, the reference bandwidth, the areas configured on the router, the types of areas (stub, totally stubby, NSSA, and totally NSSA), and area authentication.

6. Refer to the exhibit. What type of OSPF router is HQ-3?

an ABR.
an ASBR
an OSPF internal router
an OSPF edge router

Explanation: HQ-3 is in two areas, area 0 and area 1, so it is an ABR.

7. Which command will verify that a router running OSPFv3 has received a redistributed default static route from another OSPFv3 router?

default-information originate
redistribute static
show ipv6 route
show ip route

Explanation: OSPFv3 is used for IPv6 routing. When the default route is redistributed, neighboring routers will display the route source as OE2 in their IPv6 routing tables. The show ip route command is used to display the IPv4 routing table. The default-information originate command is used in the source OSPFv3 router to initiate the static route redistribution. EIGRP uses the redistribute static command.

8. A network administrator has enabled single-area OSPFv3 on a router via the ipv6 router ospf 100 command. Which command will enable this OSPFv3 process on an interface of that router?

R1(config-router)# network 192.168.10.0 0.0.0.255 area 0
R1(config-if)# ipv6 ospf 0 area 100
R1(config-if)# ipv6 ospf 100 area 0
R1(config-router)# network 192.168.10.0 0.0.0.255 area 100

Explanation: The command to enable an OSPFv3 process on a router interface is ipv6 ospf*process-id* area*area-id*. The process ID is 100 and the area ID is 0.

9. After implementing an IPv6 network, the administrator notices that the OSPFv3 process is not starting on the routers. What could be the problem?

The routers are configured with the default priority.
Authentication was not implemented between the routers.
No router IDs are configured on the routers.
The routers were not configured with the network command.

Explanation: OSPF does not need to configure any authentication to run. In an IPv6 network, if there are no IPv4 addresses configured on the router, then the router ID must be manually configured with the router-id rid command; otherwise, the OSPFv3 process does not start. OSPFV3 does not use the network command. Instead OSPFv3 is enabled directly on the interface.

10. Which command can be used by an administrator to display a list of interfaces that are enabled for OSPFv3?

show ipv6 ospf
show ipv6 neighbor
show ipv6 route ospf
show ipv6 protocols

Explanation: The show ipv6 protocols command can be used by an administrator to verify key pieces of OSPFv3 configuration information, including a list of interfaces that are enabled for OSPFv3.

11. Which OSPF LSA type provides information about IPv6 address prefixes associated with a transit network by referencing a network LSA?

Explanation: OSPF LSA type 9 provides information about IPv6 address prefixes associated with a transit network by referencing a network LSA. It also provides information about IPv6 address prefixes associated with a router by referencing a router LSA. Type 9 LSAs are flooded only within an area.

12. Refer to the exhibit. An administrator applies the configurations to routers R1 and R2 respectively. Both routers use the FastEthernet0/0 interface to connect to the same Ethernet switch. However, a neighbor adjacency fails to form. What is a possible cause for the problem?

The process IDs on R1 and R2 are identical.
The router IDs on R1 and R2 are mismatched.
The area numbers on R1 and R2 are mismatched.
The interval timers have not been set.

Explanation: Area membership is set at the interface level, and the area ID is included in the OSPF hello packet. An interface can belong to only one area. All routers within the same OSPF area maintain an identical copy of the LSDB.

“Do I Know This Already?” Quiz Answers:

1. What can be verified with the output of show ipv6 protocols? (Choose two.)

The router ID
Which areas are normal, stub, and not-so-stubby
The interfaces participating in the routing process
The ID of the designated router

2. Which of the following are true about the output of show ipv6 ospf interface brief? (Choose two.)

The cost of the interface is listed.
The DR/BDR state of the neighbor is listed.
The area an interface is participating in is listed.
The network type of the interface is listed.

3. Which IPv6 OSPFv3 command enables you to verify the configured hello interval and the dead interval?

show ip protocols
show ip ospf interface
show ip ospf neighbor
show ip ospf database

4. Which multicast addresses are used for OSPFv3? (Choose two.)

FF02::A
FF02::9
FF02::5
FF02::6

5. Which IPv6 OSPFv3 LSA is used to describe prefixes outside an area but that are still within the OSPF routing domain?

Router link states
Net link states
Inter-area prefix link states
Type 5 AS external link states

6. Which LSA type is only flooded on the local link and is not reflooded by other OSPF routers?

7. Which IPv6 OSPFv3 command enables you to verify whether an area is a stub area, totally stubby area, NSSA, or totally NSSA?

show ipv6 protocols
show ipv6 ospf
show ipv6 ospf interface
show ipv6 ospf neighbor

8. Which IPv6 OSPFv3 command enables you to verify which routers the local router has formed neighbor adjacencies with?

show ipv6 protocols
show ipv6 ospf
show ipv6 ospf interface
show ipv6 ospf neighbor

9. Which OSPFv3 address family commands are used to verify which OSPFv3 address family an interface is participating in? (Choose two.)

show ospfv3
show ospfv3 interface brief
show ospfv3 neighbor
show ospfv3 database

10. Which OSPFv3 address family debug command identifies whether there is a mismatched stub area configuration?

debug ospfv3 hello
debug ospfv3 packet
debug ospfv3 adj
debug ospfv3 events