Which parameter must match between neighboring OSPF routers in order to form an adjacency?

CCNA 3 Chapter 10 Exam Answers

Cisco CCNA 3 Simulation v6.0 Test Chapter 10

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Exam Chapter 10 Questions and Answers CCNA 3 V6.0

Which two parameters must match between neighboring OSPF routers in order to form an adjacency? (Choose two.)

Por favor, selecciona 2 respuestas correctas

network types

router ID

cost

hello / dead timers

IP address

process ID

¡ Correcto ! ¡ Incorrecto !

To form a neighbor relationship between OSPF speaking routers, the routers should reside on the same network and have the same hello and dead intervals. Others criteria that must match are area ID and network type.

Refer to the exhibit. What are three resulting DR and BDR elections for the given topology? (Choose three.)

Por favor, selecciona 3 respuestas correctas

R4 is BDR for segment B.

R5 is BDR for segment B.

R3 is BDR for segment A.

R3 is DR for segment A.

R1 is DR for segment A.

R2 is BDR for segment A.

¡ Correcto ! ¡ Incorrecto !

For segment A, R1 becomes DR because of the priority of 128 of the FastEthernet 0/0 interface. R2 becomes BDR because of the Loopback 0 interface IPv4 address.
For segment B, R3 becomes DR because of the FastEthernet 0/0 interface priority of 255. R5 becomes BDR because of the IPv4 address on the Loopback 0 interface.

Refer to the exhibit. R1 and R2 are connected to the same LAN segment and are configured to run OSPFv3. They are not forming a neighbor adjacency. What is the cause of the problem?

The timer intervals of R1 and R2 do not match.

The priority value of both R1 and R2 is 1.

The OSPFv3 process IDs of R1 and R2 are different.

The IPv6 addresses of R1 and R2 are not in the same subnet.

¡ Correcto ! ¡ Incorrecto !

There is a mismatch between the timer intervals of R1 and R2. In OSPF the timers must match on two routers before they will become neighbors. The IPv6 addresses that are used by OSPFv3 are link-local, and are in the same subnet. The OSPFv3 process ID is locally significant, and does not have to match between routers. The default OSPF interface priority value is 1, and does not prevent neighbor relationships from forming.

Refer to the exhibit. A network administrator is configuring OSPF for R1 and R2, but the adjacency cannot be established. What is the cause of the issue?

The process ID is misconfigured.

The interface s0/0/0 on router R2 is missing a link-local address.

The IP address on router R2 is misconfigured.

The area ID is misconfigured.

¡ Correcto ! ¡ Incorrecto !

To form a neighbor relationship between OSPF speaking routers, the routers should reside on the same network and have the same Hello and dead intervals. Others criteria that must match are area ID and network type. In the topology displayed, the two routers are in two different areas, thus causing an area mismatch error.

Refer to the exhibit. Which conclusion can be drawn from this OSPF multiaccess network?​

If the DR stops producing Hello packets, a BDR will be elected, and then it promotes itself to assume the role of DR.​

With an election of the DR, the number of adjacencies is reduced from 6 to 3.

​All DROTHER routers will send LSAs to the DR and BDR to multicast 224.0.0.5.

​When a DR is elected all other non-DR routers become DROTHER.

¡ Correcto ! ¡ Incorrecto !

On OSPF multiaccess networks, a DR is elected to be the collection and distribution point for LSAs sent and received. A BDR is also elected in case the DR fails. All other non-DR or BDR routers become DROTHER. Instead of flooding LSAs to all routers in the network, DROTHERs only send their LSAs to the DR and BDR using the multicast address 224.0.0.6. If there is no DR/BDR election, the number of required adjacencies is n(n-1)/2 => 4(4-1)/2 = 6. With the election, this number is reduced to 3.​

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 neighbor​

show ipv6 ospf​

show ipv6 protocols​

show ipv6 ospf interface​

¡ Correcto ! ¡ Incorrecto !

A network engineer has manually configured the hello interval to 15 seconds on an interface of a router that is running OSPFv2. By default, how will the dead interval on the interface be affected?

The dead interval will not change from the default value.

The dead interval will now be 30 seconds.

The dead interval will now be 15 seconds.

The dead interval will now be 60 seconds.

¡ Correcto ! ¡ Incorrecto !

Refer to the exhibit. Directly connected networks configured on router R1 are not being shared with neighboring routers through OSPFv3. What is the cause of the issue?

There is a mismatch of OSPF process ID in commands.

There are no network statements for the routes in the OSPF configuration.

The no shutdown command is missing on the interfaces.

IPv6 OSPF routing is not enabled.

¡ Correcto ! ¡ Incorrecto !

Unlike OSPFv2, OSPFV3 does not use the network command to advertise directly attached networks. OSPFv3 is enabled directly on the interface. These networks will be included in advertisements once the command ipv6 ospf process_id area area_id is entered on the interface. The OSPF process_id must match with the ipv6 router ospf command.

What three states are transient OPSF neighbor states that indicate a stable adjacency is not yet formed between two routers? (Choose three.)

Por favor, selecciona 3 respuestas correctas

full

loading

established

2way

exchange

exstart

¡ Correcto ! ¡ Incorrecto !

Only the full and 2way states indicate that a stable adjacency is formed.​ The loading, exstart, and exchange states are transitory states between the 2way and full states.

Which OSPF feature allows a remote OSPF area to participate in OSPF routing when it cannot connect directly to OSPF Area 0?

virtual link

DR/BDR

point-to-point connectivity

NBMA

¡ Correcto ! ¡ Incorrecto !

Which command can be used to view the OSPF hello and dead time intervals?

show ip ospf neighbor

show ip ospf route

show ip ospf interface

show ip protocols

¡ Correcto ! ¡ Incorrecto !

The OSPF hello and dead timers can be configured per interface. Hence, the correct command used to view the timers is the show ip ospf interface command. Adding the interface name and number to the command displays output for a specific interface.

A network administrator is troubleshooting an OSPFv3 configuration on an IPv6 network. The administrator issues the show ipv6 protocols command. What is the purpose for this command?

to verify OSPFv3 configuration information

to verify that the router has formed an adjacency with its neighboring routers

to display the OSPFv3 parameters configured on an interface

to display the OSPFv3 learned routes in the routing table

¡ Correcto ! ¡ Incorrecto !

There are various show commands to help troubleshoot or verify OSPFv3, including these:
show ipv6 protocols – used to verify configuration information
show ipv6 ospf neighbor – used to verify that the router has formed an adjacency with its neighboring routers
show ipv6 ospf interface – used to display the OSPFv3 parameters configured on an interface
show ipv6 route ospf – used to display only the OSPFv3 learned routes in the routing table

Match each OSPF election criterion to its sequential order for the OSPF DR and BDR election process. (Not all options are used.)

Elect the router with the highest IPv4 address on loopback interfaces. -> third
Elect the router with the highest manually configured router ID. -> second
Elect the router with the highest interface priority. -> first
Elect the router with the highest active IPv4 address on physical interfaces. -> fourth

¡ Correcto ! ¡ Incorrecto !

During the DR and BDR election process, the DR will be the one with the highest interface priority. If the priority is not manually configured, there will be a tie on the default value of 1, so the router with the highest router ID will be selected. The router ID is chosen depending on what is configured on the router. A manually configured router ID is preferred, with the highest IPv4 address on a loopback interface being preferred next, followed by the highest IPv4 address on a physical interface.

Refer to the exhibit. What three conclusions can be drawn from the displayed output? (Choose three.)

Por favor, selecciona 3 respuestas correctas

This interface is using the default priority.

The BDR has three neighbors.

The DR can be reached through the GigabitEthernet 0/0 interface.

The router ID on the DR router is 3.3.3.3

There have been 9 seconds since the last hello packet sent.

The router ID values were not the criteria used to select the DR and the BDR.

¡ Correcto ! ¡ Incorrecto !

A network administrator has just changed the router ID on a router that is working in an OSPFv2 environment. What should the administrator do to reset the adjacencies and use the new router ID?

Issue the clear ip ospf process privileged mode command.

Configure the network statements.

Change the OSPFv2 process ID.

Change the interface priority.

¡ Correcto ! ¡ Incorrecto !

Refer to the exhibit. A network administrator has configured OSPFv2 on the two Cisco routers but PC1 is unable to connect to PC2. What is the most likely problem?

Interface Fa0/0 has not been activated for OSPFv2 on router R2.

Interface Fa0/0 is configured as a passive-interface on router R2.

Interface s0/0 has not been activated for OSPFv2 on router R2.

Interface S0/0 is configured as a passive-interface on router R2.

¡ Correcto ! ¡ Incorrecto !

If a LAN network is not advertised using OSPFv2, a remote network will not be reachable. The output displays a successful neighbor adjacency between router R1 and R2 on the interface S0/0 of both routers.

Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
A network administrator is configuring multiarea OSPFv3 on the routers. The routing design requires that the router RT1 is a DROTHER for the network in Area 0 and the DR for the network in Area 1. Check the settings and status of the routers. What can the administrator do to ensure that RT1 will meet the design requirement after all routers restart?

Change the router ID to 5.5.5.5 on RT1.

Use the ipv6 ospf priority 10 command on the interface g0/2 of RT1.

Configure the loopback 0 interface with 6.6.6.6.

Restart all routers except for RT1.

Use the ipv6 ospf priority 0 command on the interface g0/0 of RT1.

¡ Correcto ! ¡ Incorrecto !

In a multiarea OSPF network, if the interface priority is the same for all routers, then the router with highest router ID becomes the DR and the router with second highest router ID becomes BDR. Changing the router ID can influence the DR/BDR election. However, for an ABR, the same router ID will be used for DR/BDR elections for multiple areas. In this case, it is better to use the interface priority value to manage the DR/BDR election for different areas, because this value is interface specific.

Refer to the exhibit. What two conclusions can be drawn based on the output of the show ipv6 route command? (Choose two.)

Por favor, selecciona 2 respuestas correctas

Routes 2001:DB8:CAFE:1::/64 and 2001:DB8:CAFE:3::/64 are advertised from the same router.

R2 receives default route information from another router.

Route 2001:DB8:CAFE:4::/64 is an external route advertised by an ASBR.

Route 2001:DB8:CAFE:B001::/64 is a route advertised by an ABR.

Route 2001:DB8:CAFE:4::/64 is advertised by a router three hops away.

¡ Correcto ! ¡ Incorrecto !

The default route ::/0 is learned from another router (signified by OE2) with the link-local address of FE80::200:CFF:FE3B:7501. The symbol OI indicates that a route is learned from an ABR. Routes 2001:DB8:CAFE:1::/64 and 2001:DB8:CAFE:3::/64 are learned from different link-local addresses and therefore are not from the same router.

When checking a routing table, a network technician notices the following entry:
O*E2 0.0.0.0/0 [110/1] via 192.168.16.3, 00:20:22, Serial0/0/0
What information can be gathered from this output?

The metric for this route is 110.

The route is located two hops away.

This route is a propagated default route.

The edge of the OSPF area 0 is the interface that is addressed 192.168.16.3.

¡ Correcto ! ¡ Incorrecto !

The metric towards this external route is one and 192.168.16.3 is the address of the next interface towards the destination.

A network engineer suspects that OSPFv3 routers are not forming neighbor adjacencies because there are interface timer mismatches. Which two commands can be issued on the interface of each OSFPv3 router to resolve all timer mismatches? (Choose two.)

Por favor, selecciona 2 respuestas correctas

no ipv6 ospf hello-interval

no ipv6 ospf dead-interval

no ipv6 router ospf 10

ip ospf dead-interval 40

ip ospf hello-interval 10

no ipv6 ospf cost 10

¡ Correcto ! ¡ Incorrecto !

The no ipv6 ospf hello-interval and no ipv6 ospf dead-interval commands issued on each OSPFv3 interface will reset the intervals to the respective default periods. This ensures that the timers on all routers now match and, providing other appropriate configurations are correct, the routers will form adjacencies. The ip ospf hello-interval 10 and ip ospf dead-interval 40 commands are OPSFv2 commands that are used for IPv4 routing. If the ipv6 ospf hello-interval and ipv6 ospf dead-interval commands are used, then the interval has to be specified in seconds. The parameter default is not valid in these commands.

Refer to the exhibit. What the amount of time that has elapsed since the router received a hello packet?

4 seconds

6 seconds

40 seconds

10 seconds

¡ Correcto ! ¡ Incorrecto !

The show ip ospf interface command is used to display the OSPF parameters configured on an interface like the process ID; router ID; area, and so forth. In the exhibit the router has a default hello interval of 10 seconds. It also displays that the next hello is due in 6 seconds. Hence, the time elapsed is 4 seconds.

Which command will a network engineer issue to verify the configured hello and dead timer intervals on a point-to-point WAN link between two routers that are running OSPFv2?

show ipv6 ospf interface serial 0/0/0

show ip ospf neighbor

show ip ospf interface serial 0/0/0

show ip ospf interface fastethernet 0/1

¡ Correcto ! ¡ Incorrecto !

The show ip ospf interface serial 0/0/0 command will display the configured hello and dead timer intervals on a point-to-point serial WAN link between two OSPFv2 routers. The show ipv6 ospf interface serial 0/0/0 command will display the configured hello and dead timer intervals on a point-to-point serial link between two OSPFv3 routers. The show ip ospf interface fastethernet 0/1 command will display the configured hello and dead timer intervals on a multiaccess link between two (or more) OSPFv2 routers. The show ip ospf neighbor command will display the dead interval elapsed time since the last hello message was received, but does not show the configured value of the timer.

Open the PT Activity. Perform the tasks in the activity instructions and then answer the question. Which routers are the DR and BDR in this topology?

DR:R1 BDR:R2

DR:R3 BDR:R6

DR:R3 BDR:R5

DR:R6 BDR:R5

DR:R4 BDR:R1

DR:R5 BDR:R3

¡ Correcto ! ¡ Incorrecto !

Once OSPF neighbor adjacencies have formed, use the show ip ospf neighbors command to determine which router was elected the DR and which router was elected the BDR. In this scenario, R3 was elected the DR because it had the highest priority (10). R5 was elected the BDR because it had the highest router ID among eligible routers (5.5.5.5). R6 was not eligible to become the BDR because its priority was set to 0.

CCNA 3 Chapter 10 v6 Exam Answers

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What values must match between two Neighbouring routers to form an OSPF adjacency?

From the perspective of OSPF, there are a couple of things that must match for a OSPF neighborship to establish; these include:.
The devices must be in the same area..
The devices must have the same authentication configuration..
The devices must be on the same subnet..
The devices hello and dead intervals must match..

What must match between the two routers for them to form an adjacency?

For two OSPF routers to form an adjacency, they must be in the same area, must be in the same subnet, and must have authentication information match, if configured.

Which three OSPF states are involved when two routers are forming an adjacency?

The Down, Init, and Two-way states are involved in the phase of neighboring router adjacency establishment.

What is OSPF neighbor adjacency?

OSPF adjacency is formed betwen selected neighbors and allows them to exchange routing information. So, two routers must first be neighbors, only then they can become adjacent. Two routers become adjacent if: At least one of them is DR or BDR (on multiaccess type networks), or.

What would prevent two OSPF routers from forming an adjacency?

Explanation: 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.

Which command will verify that a router that is running OSPFv2 has formed an adjacency?

The show ip ospf neighbor command is used to verify that the router has formed an adjacency with its neighboring routers.

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