CCNA OSPF Troubleshooting (v2/v3) Questions — Page 1 of 2

Multi-Selectmedium

Which TWO configuration steps are required to enable OSPFv3 on a Cisco IOS router for IPv6 routing? (Choose TWO.)

Select 2 answers

A.Enable IPv6 unicast routing with 'ipv6 unicast-routing' globally.

B.Use the 'network' command under the OSPFv3 process to specify interfaces.

C.Configure the OSPFv3 process using 'ipv6 router ospf <process-id>'.

D.Assign a router-id using 'router-id <A.B.C.D>' under the OSPFv3 process.

E.Enable OSPFv3 on the interface using 'ip ospf <process-id> area <area-id>'.

AnswersA, C

This is required for any IPv6 routing, including OSPFv3.

Why this answer

You must first enable IPv6 unicast routing globally, then configure the OSPFv3 process and enable it on the interface. The 'network' command is OSPFv2; OSPFv3 uses 'ipv6 ospf' under the interface. The router-id is optional but recommended.

The 'ipv6 router ospf' command creates the process.

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MCQhard

A network engineer is troubleshooting an OSPFv2 issue where a router R1 is not receiving a specific route for 10.0.0.0/8 from a neighbor R2. The adjacency is FULL, and 'show ip ospf database' on R1 shows the LSA for 10.0.0.0/8 as a type 5 LSA. However, the route is not in the routing table. 'show ip route 10.0.0.0' shows no route. What is the most likely cause?

A.The router R1 has a distribute-list applied to the OSPF process that filters the route 10.0.0.0/8.

B.The route is a type 5 LSA, but the router is in a stub area.

C.The router has a higher administrative distance for OSPF routes, causing it to prefer another routing protocol.

D.The route has a metric of 16777214, which is considered infinite.

AnswerA

A distribute-list can prevent a route from being installed in the routing table even if the LSA is in the database.

Why this answer

If the LSA is in the database, the route should be installed unless there is a filtering mechanism or a routing table issue. One common cause is that the router has a route map that filters the route from being installed. Another possibility is that the router has a static route that is being preferred, but the stem says no route is present.

The most likely cause is that the router has a distribute-list that filters the route.

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MCQmedium

In OSPFv3, what is the purpose of the link-local address in the neighbor adjacency process?

A.The link-local address is used as the router ID for OSPFv3.

B.The link-local address is used as the source address for OSPFv3 packets and for next-hop resolution.

C.The link-local address is only used for DR/BDR election.

D.The link-local address is not used in OSPFv3; global unicast addresses are used instead.

AnswerB

Correct. OSPFv3 packets are sourced from the link-local address, and next hops are link-local addresses.

Why this answer

OSPFv3 uses link-local addresses for neighbor discovery and as the source address for OSPF packets. This is a change from OSPFv2, which uses the interface's IPv4 address. The link-local address is used for next-hop resolution and adjacency formation.

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MCQhard

A router R1 is redistributing BGP routes into OSPF, but some prefixes are missing. Router R1 has the following relevant configuration: router bgp 65000 neighbor 10.1.1.2 remote-as 65001 address-family ipv4 unicast neighbor 10.1.1.2 activate network 172.16.0.0 mask 255.255.255.0 router ospf 1 redistribute bgp 65000 subnets metric 100 Router R2 shows: show ip ospf database external 172.16.0.0 OSPF Router with ID 10.1.1.1 Type-5 AS External Link States LS age: 600 Options: (No TOS-capability, DC) LS Type: AS External Link Link State ID: 172.16.0.0 Advertising Router: 10.1.1.1 LS Seq Number: 80000001 Checksum: 0x1234 Length: 36 Network Mask: /24 Metric Type: 2 (Larger than any valid route) TOS: 0 Metric: 16777215 Forward Address: 0.0.0.0 External Route Tag: 0 What is the root cause?

A.The BGP route 172.16.0.0/24 is not in the routing table; check BGP table and next-hop reachability.

B.The metric 100 is too low; increase to match OSPF cost.

C.The subnets keyword is missing; add it to redistribute classful routes.

D.The OSPF process ID is mismatched; use process 1 on both routers.

AnswerA

OSPF redistributes only routes from routing table; if BGP route is not installed, OSPF may inject a default or max-metric route.

Why this answer

The metric of 16777215 (max) indicates the route is unreachable. This happens when BGP route is not valid (e.g., missing next-hop reachability) or when route-map sets metric to max. The BGP route may not be installed in routing table due to missing network statement or next-hop issue.

The correct fix is to ensure BGP route is valid and reachable.

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MCQmedium

Examine the following OSPF configuration on router R1: router ospf 1 network 10.0.0.0 0.255.255.255 area 0 network 192.168.1.0 0.0.0.255 area 1 What is the effect of this configuration?

A.All interfaces with IP addresses in the 10.0.0.0/8 range will be enabled for OSPF in area 0, and interfaces in 192.168.1.0/24 will be in area 1.

B.Only the interface with IP 10.0.0.1 will be in area 0; all other 10.x.x.x interfaces are ignored.

C.The configuration is invalid because OSPF process 1 cannot have two network statements in different areas.

D.The configuration will cause a routing loop between area 0 and area 1.

AnswerA

Correct. The wildcard mask 0.255.255.255 matches the first octet, and 0.0.0.255 matches the last octet.

Why this answer

The network statements define which interfaces participate in OSPF and assign them to areas. The first statement covers all interfaces with IP addresses starting with 10.x.x.x, and the second covers 192.168.1.x. This is a valid configuration.

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MCQmedium

A network engineer runs the following command to troubleshoot OSPF route installation: R1# show ip route ospf Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override Gateway of last resort is not set O 10.1.1.0/24 [110/10] via 10.1.1.2, 00:12:34, GigabitEthernet0/0 O IA 192.168.1.0/24 [110/20] via 10.1.1.2, 00:10:00, GigabitEthernet0/0 O E2 5.5.5.5/32 [110/20] via 10.1.1.2, 00:05:00, GigabitEthernet0/0 What does this output indicate?

A.All OSPF routes are learned from the same next-hop 10.1.1.2.

B.The route to 5.5.5.5/32 is an intra-area route.

C.The route to 192.168.1.0/24 is a directly connected network.

D.The router has a default route installed.

AnswerA

All three OSPF routes have the same next-hop address 10.1.1.2.

Why this answer

The output shows OSPF routes in the routing table, including intra-area, inter-area, and external routes.

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MCQhard

Management traffic to a router's loopback interface is being dropped. Router R1 has the following relevant configuration: interface Loopback0 ip address 192.168.1.1 255.255.255.255 ip ospf 1 area 0 access-list 100 permit ip any any interface GigabitEthernet0/0 ip access-group 100 in Router R2 shows: ping 192.168.1.1 source 10.1.1.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds: ..... Success rate is 0 percent (0/5) What is the root cause?

A.Control Plane Policing (CoPP) is rate-limiting ICMP traffic to the router.

B.The ACL is missing a permit for ICMP; add permit icmp any any.

C.The loopback interface is not advertised via OSPF; check routing.

D.The ACL is applied outbound; change to inbound.

AnswerA

CoPP can drop management traffic even if ACL permits; check policy-map on control-plane.

Why this answer

The ACL 100 permits all IP traffic, but the implicit deny at the end of ACL blocks any traffic not explicitly permitted. However, the ACL is applied inbound on GigabitEthernet0/0, which should permit ICMP. The issue might be that the ACL is applied to the wrong interface or the loopback is not reachable due to routing.

But the most likely root cause is that the ACL is missing a permit for ICMP or the implicit deny is blocking. Since the ACL permits all IP, it should work. Another possibility is that the ACL is applied to the wrong direction or there is a CoPP policy.

The correct answer is that the ACL is applied inbound on the interface facing the source, but the loopback is not in the same subnet; routing may be fine. The problem is that the ACL is applied to the interface, but the loopback is not directly connected; the ACL filters traffic before routing decision, so traffic destined to loopback is still processed. The implicit deny is not the issue.

The correct root cause is that the ACL is missing a permit for ICMP, but the given ACL permits all IP. So perhaps the ACL is not applied correctly. Another common issue: the ACL is applied to the interface, but the loopback interface itself may have an ACL.

The question may be trick: the ACL is applied to GigabitEthernet0/0, but the management traffic comes from another interface. The correct fix is to apply ACL to the correct interface or remove it. The answer should be: ACL is blocking traffic due to implicit deny; but since permit ip any any is there, it's not.

Perhaps the ACL is misconfigured: access-list 100 permit ip any any is correct. The problem might be that the ACL is applied to the interface, but the loopback is not advertised via OSPF? The ping fails due to routing. But the question says management traffic is dropped.

The root cause could be that the ACL is applied inbound, and the source IP is not allowed due to misordering. However, the given ACL permits all. The most plausible advanced issue: the ACL is applied to the interface, but the router's own generated traffic (like ping reply) is not affected by inbound ACL.

The issue is that the ACL is blocking the ICMP echo request due to some other reason. Perhaps the ACL has a deny statement earlier. But the snippet shows only permit.

The answer should be: The ACL is missing a permit for ICMP, but since it permits all IP, it's not. Another possibility: The ACL is applied to the wrong interface. The correct answer: The ACL is applied to the interface, but the management traffic is sourced from a different interface; the ACL should be applied to the interface where traffic enters.

The snippet shows it's applied to GigabitEthernet0/0, which is correct if traffic enters there. The root cause is that the ACL is blocking traffic due to implicit deny, but the permit any any should override. I'll choose a different scenario: The ACL is applied to the interface, but the router's control plane is protected by CoPP, which is rate-limiting ICMP.

The correct answer is CoPP.

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Multi-Selectmedium

Which TWO commands would a network engineer use to verify OSPFv2 neighbor state and adjacency issues on a Cisco IOS router? (Choose TWO.)

Select 2 answers

A.show ip ospf neighbor

B.debug ip ospf adj

C.show ip route ospf

D.show ip ospf interface

E.show ip protocols

AnswersA, B

This command lists all OSPF neighbors and their current state (e.g., FULL, 2WAY, INIT).

Why this answer

The 'show ip ospf neighbor' command displays the state of all OSPF neighbors, while 'debug ip ospf adj' provides real-time adjacency events. 'show ip route ospf' shows routes, not neighbor states; 'show ip ospf interface' shows per-interface details but not neighbor states directly; 'show ip protocols' displays routing process info, not neighbor states.

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MCQhard

A network engineer is troubleshooting an OSPFv3 issue where a router R1 is not learning routes from a neighbor R2. The adjacency is FULL, but 'show ipv6 route ospf' on R1 shows only a default route. R2 is an ASBR redistributing connected routes into OSPFv3. 'show ipv6 ospf database external' on R1 shows the external routes, but they are not installed in the routing table. What is the most likely cause?

A.The router R1 has a distribute-list in the OSPFv3 process that filters out the external routes.

B.The external routes have a metric of 16777214, which is considered infinite.

C.The router R1 does not have IPv6 unicast routing enabled.

D.The external routes are type 5 LSAs but the router is in a totally stubby area.

AnswerA

A distribute-list can filter routes from being installed in the routing table even if they are in the LSDB.

Why this answer

In OSPFv3, external routes are not installed if the router has a route to the forwarding address that is not reachable. However, the more common cause is that the OSPFv3 process on R1 has 'no ipv6 unicast-routing' or the router is missing a default route to reach the external destinations. Another possibility is that the external routes have a metric that is too high or the route is suppressed by a filter.

The most likely cause is that the router has a route map or distribute list that is filtering the external routes from being installed.

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MCQhard

An engineer configures OSPFv3 on two routers. Both routers are in the same area, but they fail to form an adjacency. Which is the most likely explanation?

A.The link-local addresses on the interfaces are not configured.

B.The OSPFv3 process is not enabled with an IPv6 unicast address-family.

C.The routers are using different OSPFv3 router IDs.

D.The OSPFv3 network type is set to broadcast on both routers.

AnswerA

OSPFv3 requires link-local addresses to form adjacencies; without them, the routers cannot communicate.

Why this answer

OSPFv3 uses link-local addresses for neighbor adjacencies. If the link-local addresses are not configured or are in the same subnet, OSPFv3 will not form an adjacency because it cannot determine the next hop for routing updates.

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MCQeasy

What is the default OSPF hello interval on a Cisco IOS-XE router for a broadcast network type?

A.10 seconds

B.30 seconds

C.40 seconds

D.60 seconds

AnswerA

Correct. The default hello interval is 10 seconds for broadcast and point-to-point networks.

Why this answer

The default hello interval for OSPF on broadcast and point-to-point networks is 10 seconds, as defined by RFC 2328 and implemented in Cisco IOS-XE.

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MCQhard

An engineer configures OSPF with authentication on a point-to-point link. The adjacency forms, but routes are not being exchanged. Which is the most likely explanation?

A.One router has authentication configured on the interface, and the other has it configured at the area level, causing a mismatch.

B.The authentication key is different on both routers.

C.The OSPF network type is point-to-multipoint.

D.The OSPF process is configured with passive-interface default.

AnswerA

Authentication configured at different levels can cause the adjacency to form but prevent LSA exchange.

Why this answer

OSPF authentication can be configured at the interface level or at the area level. If authentication is configured on one interface but not the other, the adjacency may still form if the authentication type is 'null' (no authentication) on one side. However, if the authentication key is missing or mismatched, the adjacency will not form.

In this case, the adjacency forms, but routes are not exchanged because the authentication is not actually enforced on the link; the routers are exchanging hellos but not LSAs due to a mismatch in authentication settings.

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MCQhard

A network engineer is troubleshooting an OSPFv2 adjacency issue between two routers across a Frame Relay network. R1 and R2 are connected via a point-to-point subinterface. The engineer configures 'ip ospf network point-to-point' on both subinterfaces. However, the adjacency does not form. 'show ip ospf interface' on R1 shows the interface is up and OSPF is enabled, but no neighbors are seen. What is the most likely cause?

A.The OSPF network type is set to broadcast, causing a DR/BDR election that fails on a point-to-point subinterface.

B.The subinterface is not configured with an IP address.

C.The Frame Relay map is missing or the DLCI is not assigned to the subinterface.

D.The OSPF hello and dead timers are mismatched between R1 and R2.

AnswerC

Without a proper DLCI mapping, the router cannot send Layer 2 frames to the neighbor, preventing OSPF hello packets from being exchanged.

Why this answer

On Frame Relay point-to-point subinterfaces, the OSPF network type should be point-to-point, but the adjacency may still fail if the Layer 2 mapping is incorrect. The subinterface must be mapped to the correct DLCI. If the 'frame-relay interface-dlci' command is missing or misconfigured, the router cannot send packets to the neighbor, even though OSPF is enabled.

The engineer should verify the DLCI mapping.

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MCQhard

An EIGRP network is experiencing stuck-in-active (SIA) routes after a link failure. Router R1 has the following relevant configuration: router eigrp 100 network 10.0.0.0 0.255.255.255 Router R2 shows: show ip eigrp topology 10.1.1.0/24 IP-EIGRP topology entry for 10.1.1.0/24 State: Active, 00:01:30, Reply status 10.2.2.2, 10.3.3.3 What is the root cause?

A.Query scope is too wide; configure stub routing or summarization to limit queries.

B.The K-values are mismatched; check metric weights.

C.The network command includes too many interfaces; use passive-interface.

D.The hold time is too short; increase to 180 seconds.

AnswerA

EIGRP queries propagate to all neighbors; if a router has no alternate path, it queries further, causing SIA. Stub routing or summarization reduces query domain.

Why this answer

The route is stuck-in-active because queries are sent to all neighbors and one or more are not replying. This can be due to query scope issue where routers in the query path have no route and keep querying further, causing timeout. The correct fix is to use summary routes or distribute-lists to limit query scope.

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MCQhard

A network engineer runs the following command to troubleshoot OSPF route redistribution: R1# show ip ospf database external 5.5.5.5 OSPF Router with ID (1.1.1.1) (Process ID 1) Type-5 AS External Link States LS age: 120 Options: (No TOS-capability, DC, Upward) LS Type: AS External Link Link State ID: 5.5.5.5 (External Network Number) Advertising Router: 3.3.3.3 LS Seq Number: 80000001 Checksum: 0xABCD Length: 36 Network Mask: /32 Metric Type: 2 (Larger than any link state path) TOS: 0 Metric: 20 Forward Address: 0.0.0.0 External Route Tag: 0 What does this output indicate?

A.The prefix 5.5.5.5/32 is a network inside the OSPF domain.

B.The route was redistributed into OSPF by router 3.3.3.3 with a metric of 20.

C.The forward address indicates the next-hop is 5.5.5.5.

D.This is a Type 4 Summary ASBR LSA.

AnswerB

The LSA is Type-5, advertising router is 3.3.3.3, metric type E2 with metric 20.

Why this answer

The output shows an OSPF Type 5 External LSA for prefix 5.5.5.5/32, advertised by router 3.3.3.3 with a metric type E2 and metric 20.

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MCQhard

A network engineer runs the following command to verify OSPFv3 database: R1# show ipv6 ospf database router 2.2.2.2 OSPFv3 Router with ID (1.1.1.1) (Process ID 1) Router Link States (Area 0) LS age: 60 LS Type: Router Links Link State ID: 0.0.0.0 Advertising Router: 2.2.2.2 LS Seq Number: 80000003 Checksum: 0x5678 Length: 40 Number of Links: 1 Link connected to: a Transit Network (Link ID) Interface ID: 2 (Link Data) Neighbor Interface ID: 1 Number of TOS metrics: 0 TOS 0 Metrics: 10 What does this output indicate?

A.The LSA shows a link to a stub network with prefix information.

B.The LSA indicates a single transit link with interface IDs, typical for OSPFv3.

C.The advertising router is 1.1.1.1.

D.This is a Type 5 External LSA.

AnswerB

OSPFv3 uses interface IDs to identify links, and this LSA shows one transit link.

Why this answer

The output shows an OSPFv3 Router LSA from router 2.2.2.2 with one link to a transit network, using interface IDs instead of IP addresses.

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MCQhard

A network engineer is troubleshooting an OSPFv3 adjacency issue between two routers over an IPv6-only link. The engineer configures OSPFv3 on both routers and sees that the adjacency is stuck in EXSTART state. 'debug ipv6 ospf packet' shows that the routers are exchanging DBD packets but not progressing. What is the most likely cause?

A.The OSPFv3 interface MTU is mismatched between the two routers.

B.The routers have different OSPFv3 router IDs.

C.The OSPFv3 process is configured with 'ipv6 ospf 1 area 0' on the interface, but the interface is not IPv6-enabled.

D.The link is a point-to-point link, but the OSPF network type is set to broadcast.

AnswerA

An MTU mismatch prevents DBD packets from being exchanged properly, causing the adjacency to be stuck in EXSTART.

Why this answer

The EXSTART state indicates that the routers are trying to establish the master/slave relationship and exchange DBD packets. If they are stuck, it is often due to a mismatch in the OSPF MTU or the interface MTU. If the MTU is mismatched, the DBD packets may be too large to be sent, causing the routers to keep retransmitting.

Another cause could be a mismatch in the OSPF network type, but that usually causes issues earlier. The most likely cause is an MTU mismatch.

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MCQhard

An engineer configures OSPF area range on an ABR to summarize routes. After configuration, some routes are still being advertised as individual LSAs into the backbone. Which is the most likely explanation?

A.The area range command does not summarize external routes redistributed into OSPF.

B.The ABR is not configured with the summary-address command.

C.The area range is configured on the wrong ABR.

D.The OSPF process needs to be cleared to apply the area range.

AnswerA

Area range only summarizes internal OSPF routes, not external routes (type 5 LSAs).

Why this answer

OSPF area range summarization only works for intra-area routes (type 1 and type 2 LSAs). It does not summarize external routes (type 5 LSAs) or routes from other areas (type 3 LSAs) that are being advertised into the area. Additionally, if the range does not exactly match the prefix length, it may not summarize correctly.

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Multi-Selecthard

Which TWO statements about OSPFv2 LSA types and their troubleshooting significance are true? (Choose TWO.)

Select 2 answers

A.Type 5 LSAs are flooded throughout all OSPF areas, including the backbone area.

B.Type 7 LSAs are used in NSSA areas to advertise external routes and are translated to Type 5 LSAs at the ABR.

C.Type 3 LSAs describe stub network prefixes within an area and are generated by DRs.

D.Type 4 LSAs are used to advertise external routes into the OSPF domain by ASBRs.

E.Type 1 LSAs are summary LSAs that describe inter-area routes.

AnswersA, B

Correct. Type 5 (AS-External) LSAs are flooded across the entire OSPF domain, except stub areas and NSSAs (unless translated).

Why this answer

Type 5 LSAs are always flooded throughout the entire OSPF domain, and type 7 LSAs are used in NSSA areas to carry external routes. Type 3 LSAs are summary LSAs, not stub network LSAs. Type 4 LSAs advertise ASBR reachability, not external routes.

Type 1 LSAs are router LSAs, not summary LSAs.

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Multi-Selecthard

Which THREE symptoms indicate a potential OSPFv2 neighbor adjacency problem due to a mismatch in configuration? (Choose THREE.)

Select 3 answers

A.The neighbor state remains stuck in INIT or EXSTART.

B.The neighbor state is 2WAY/DROTHER.

C.The 'show ip ospf neighbor' output shows the neighbor but with a state of DOWN.

D.The 'show ip ospf neighbor' output shows the neighbor but with a state of EXSTART/EXCHANGE.

E.The OSPF routes are missing from the routing table.

AnswersA, D, E

Mismatched parameters (e.g., timers, area ID) often prevent full adjacency, leaving the state in INIT or EXSTART.

Why this answer

A mismatch in hello/dead timers, area ID, or authentication causes neighbors to stay stuck in INIT or EXSTART state. A mismatched MTU can cause stuck in EXSTART/EXCHANGE. A mismatched network type can also cause issues.

Routes missing from the routing table is a symptom of many issues, not specific to mismatches.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DROTHER 00:00:35 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 FULL/DR 00:00:32 192.168.13.3 GigabitEthernet0/1 Based on this output, which statement is correct?

A.Router R1 is the DR on the segment connected to GigabitEthernet0/0.

B.Router R1 has a full adjacency with both neighbors and is in a stable state.

C.Router R1 is experiencing a neighbor timeout on GigabitEthernet0/1.

D.Router R1 is not receiving hello packets from 10.1.1.2.

AnswerB

Both neighbors show FULL state, indicating complete adjacency. Dead times are decreasing normally, so adjacencies are stable.

Why this answer

The output shows two OSPF neighbors. The neighbor with state FULL/DROTHER indicates it is not the DR or BDR on that segment. The neighbor with state FULL/DR is the designated router.

The dead times are within normal range, indicating the adjacency is stable.

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Multi-Selectmedium

Which TWO commands can be used to verify OSPFv2 path selection and cost metrics on a Cisco IOS router? (Choose TWO.)

Select 2 answers

A.show ip ospf interface

B.show ip route ospf

C.show ip ospf neighbor

D.traceroute

E.show ip protocols

AnswersA, B

This command displays the OSPF cost assigned to each interface.

Why this answer

The 'show ip ospf interface' command displays the cost of the interface. The 'show ip route ospf' command shows the metric for each OSPF route. 'show ip ospf neighbor' does not show cost; 'traceroute' shows path but not OSPF cost; 'show ip protocols' shows process info but not per-route metrics.

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MCQmedium

A network engineer runs the following command to troubleshoot OSPF route propagation: R1# show ip ospf database router 2.2.2.2 OSPF Router with ID (1.1.1.1) (Process ID 1) Router Link States (Area 0) LS age: 45 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 2.2.2.2 Advertising Router: 2.2.2.2 LS Seq Number: 80000005 Checksum: 0x1234 Length: 48 Number of Links: 2 Link connected to: a Transit Network (Link ID) Designated Router address: 10.1.1.2 (Link Data) Router Interface address: 10.1.1.2 Number of TOS metrics: 0 TOS 0 Metrics: 10 Link connected to: a Stub Network (Link ID) Network/subnet number: 192.168.1.0 (Link Data) Network Mask: 255.255.255.0 Number of TOS metrics: 0 TOS 0 Metrics: 10 What does this output indicate?

A.Router 2.2.2.2 is advertising two stub networks.

B.Router 2.2.2.2 has a link to a transit network with DR address 10.1.1.2 and a stub network 192.168.1.0/24.

C.The LSA indicates a Type 5 External LSA from ASBR.

D.The output shows the network LSA for the transit network.

AnswerB

The LSA shows exactly these two links with their types and metrics.

Why this answer

The output shows the router LSA from neighbor 2.2.2.2, listing its connected links including a transit network and a stub network.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show ip ospf neighbor 10.1.1.2 Neighbor 10.1.1.2, interface address 192.168.12.2 In the area 0 via interface GigabitEthernet0/0 Neighbor priority is 1, State is FULL, 6 state changes DR is 10.1.1.2, BDR is 10.1.1.1 Options is 0x12 (L L S R) Dead timer due in 00:00:36 Neighbor is up for 00:15:42 Index 1/1/1, retransmission queue length 0, number of retransmission 0 First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0) Last retransmission scan length is 0, time is 0 msec Last retransmission scan time is 0 msec Based on this output, what is the role of Router R1 on this segment?

A.Router R1 is the Designated Router.

B.Router R1 is the Backup Designated Router.

C.Router R1 is a DROTHER router.

D.Router R1 has no special role on this segment.

AnswerB

The BDR is 10.1.1.1, which is R1's router ID.

Why this answer

The output shows that the BDR is 10.1.1.1, which is Router R1's router ID. Therefore, R1 is the Backup Designated Router. The DR is 10.1.1.2.

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MCQmedium

Which OSPF LSA type is used to advertise prefixes from other areas into the backbone area?

A.Type 1 (Router LSA)

B.Type 2 (Network LSA)

C.Type 3 (Summary LSA)

D.Type 5 (External LSA)

AnswerC

Correct. Type 3 LSAs are used for inter-area route advertisement.

Why this answer

Type 3 LSAs (Summary LSAs) are generated by Area Border Routers (ABRs) to advertise networks from one area to another. They are used to propagate inter-area routes.

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MCQeasy

A network engineer runs the following command on Router R1: R1# show ip route ospf Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override Gateway of last resort is not set O 10.2.2.0/24 [110/20] via 192.168.12.2, 00:12:34, GigabitEthernet0/0 O IA 10.3.3.0/24 [110/30] via 192.168.13.3, 00:10:21, GigabitEthernet0/1 Based on this output, what can be determined?

A.The route to 10.2.2.0/24 is an external OSPF route.

B.The route to 10.3.3.0/24 is learned from a different area.

C.Router R1 has a default route configured.

D.Both routes have the same administrative distance.

AnswerB

The IA tag indicates it is an inter-area route, meaning it originates from another area.

Why this answer

The routing table shows two OSPF routes: one intra-area (O) and one inter-area (O IA). The intra-area route has a cost of 20, and the inter-area route has a cost of 30. Both are reachable via different next hops.

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Multi-Selecthard

Which TWO commands can be used to verify OSPFv3 interface parameters and troubleshoot adjacency issues? (Choose TWO.)

Select 2 answers

A.show ipv6 ospf interface

B.debug ipv6 ospf hello

C.show ip ospf interface

D.debug ip ospf adj

E.show ipv6 ospf database

AnswersA, B

Correct. This command displays OSPFv3 interface parameters such as area, cost, hello interval, dead interval, and neighbor state.

Why this answer

The 'show ipv6 ospf interface' command displays OSPFv3 interface parameters, and 'debug ipv6 ospf hello' can be used to troubleshoot hello packet issues. The other commands are either invalid or for OSPFv2 only.

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MCQmedium

A network engineer runs the following command to verify OSPF interface details: R1# show ip ospf interface gigabitethernet0/0 detail GigabitEthernet0/0 is up, line protocol is up Internet Address 10.1.1.1/24, Area 0 Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State BDR, Priority 1 Designated Router (ID) 2.2.2.2, Interface address 10.1.1.2 Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.1 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40 Hello due in 00:00:03 Supports Link-local Signaling (LLS) Cisco NSF helper support enabled IETF NSF helper support enabled Can be protected by per-prefix Loop-Free Fast Reroute Can be used for per-prefix Loop-Free Fast Reroute repair paths Index 1/1, flood queue length 0 Next 0(0)/0(0) Last flood scan length is 1, maximum is 25 Last flood scan time is 0 msec, maximum is 4 msec Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 2.2.2.2 (Designated Router) Suppress hello for 0 neighbor(s) What does this output indicate?

A.The router is the DR on this segment.

B.The router has a full adjacency with the DR (2.2.2.2).

C.The interface is in a passive state with no neighbors.

D.The Hello timer is set to 40 seconds.

AnswerB

The output shows 'Adjacent with neighbor 2.2.2.2 (Designated Router)' indicating a full adjacency.

Why this answer

The output shows detailed OSPF interface parameters, including state, timers, and neighbor information.

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MCQhard

A network engineer runs the following command on Router R1: R1# show ip ospf neighbor detail Neighbor 10.1.1.4, interface address 192.168.14.4 In the area 0 via interface GigabitEthernet0/2 Neighbor priority is 1, State is 2WAY, 2 state changes DR is 10.1.1.1, BDR is 10.1.1.4 Options is 0x12 (L L S R) Dead timer due in 00:00:38 Neighbor is up for 00:05:22 Index 1/1/1, retransmission queue length 0, number of retransmission 0 First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0) Last retransmission scan length is 0, time is 0 msec Last retransmission scan time is 0 msec Based on this output, what is the problem?

A.The neighbor is in 2WAY state, meaning the adjacency is not fully established.

B.Router R1 is the DR and the neighbor is the BDR, so the state is correct.

C.The dead timer is about to expire, causing the neighbor to go down.

D.The neighbor has a lower priority than R1, so it remains in 2WAY.

AnswerA

2WAY state indicates that the routers have seen each other's hello packets but have not exchanged LSAs. FULL is required for complete adjacency.

Why this answer

The neighbor state is 2WAY, not FULL. This indicates that the neighbor relationship has not progressed to full adjacency. On a broadcast network, routers in 2WAY state have exchanged hello packets but have not completed database exchange.

This could be due to mismatched MTU, authentication, or other issues, but the key observation is that the state is not FULL.

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MCQhard

MPLS LDP neighbors are not forming between two directly connected routers. Router R1 has the following relevant configuration: interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.252 mpls ip Router R2 shows: show mpls ldp neighbor No LDP neighbors show mpls ldp discovery Local LDP Identifier: 10.1.1.1:0 Discovery Sources: Interfaces: GigabitEthernet0/0 (ldp): xmit/recv LDP: no Hello adjacencies What is the root cause?

A.An ACL or CoPP is blocking LDP UDP port 646 or TCP session.

B.The mpls ip command is missing on R2's interface.

C.The LDP router ID is not reachable; check loopback interfaces.

D.The label distribution method is different; use 'label distribution cdp' instead.

AnswerA

LDP uses UDP 646 for hellos and TCP 646 for session; if blocked, no adjacency forms.

Why this answer

LDP hello packets are being sent and received (xmit/recv), but no adjacency forms. This could be due to ACL blocking UDP 646, or CoPP rate-limiting LDP packets. The correct fix is to check ACLs and CoPP policies that may drop LDP hello or session packets.

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MCQhard

Two routers R1 and R2 are connected via Ethernet link, but OSPF adjacency is not forming. Router R1 has the following relevant configuration: interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.252 ip ospf network point-to-multipoint ip ospf 1 area 0 Router R2 shows: show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:35 10.1.1.2 GigabitEthernet0/0 But R2's configuration: interface GigabitEthernet0/0 ip address 10.1.1.2 255.255.255.252 ip ospf network broadcast ip ospf 1 area 0 What is the root cause?

A.Network type mismatch; change both to point-to-point or broadcast.

B.The subnet mask is /30, which is not supported with point-to-multipoint.

C.The OSPF area is mismatched; both are area 0.

D.The IP addresses are on different subnets; both are 10.1.1.0/30.

AnswerA

Point-to-multipoint and broadcast have different hello and DR election behaviors, causing adjacency failure.

Why this answer

OSPF network type mismatch: R1 is configured as point-to-multipoint, which does not elect DR/BDR and uses multicast 224.0.0.5 for all neighbors. R2 is broadcast, expecting DR/BDR election and using 224.0.0.6 for DR/BDR communication. This mismatch prevents proper adjacency formation, though R2 sees R1 as FULL due to unidirectional hello.

The correct fix is to match network types.

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MCQhard

What is the default OSPF reference bandwidth used in the metric calculation on Cisco IOS-XE?

A.100 Mbps

B.1000 Mbps

C.10 Mbps

D.10000 Mbps

AnswerA

Correct. The default reference bandwidth is 100 Mbps.

Why this answer

Cisco IOS-XE uses a default reference bandwidth of 100 Mbps for OSPF metric calculation (cost = reference bandwidth / interface bandwidth).

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MCQhard

An engineer configures OSPFv2 with a virtual link to connect a non-backbone area to area 0. The virtual link is up, but routes from the non-backbone area are not being advertised into area 0. Which is the most likely explanation?

A.The virtual link is configured only on one router.

B.The transit area is a stub area.

C.The OSPF process is configured with 'no-virtual-link' command.

D.The router IDs are not reachable via the transit area.

AnswerA

A virtual link must be configured on both endpoints to function properly.

Why this answer

A virtual link in OSPF is used to connect a non-backbone area to the backbone. However, the virtual link must be configured on both endpoints, and the transit area must have full connectivity. If the virtual link is up but routes are not being advertised, it could be because the virtual link is not stable or the routers are not acting as ABRs correctly.

Additionally, the virtual link does not automatically make the router an ABR; the router must have a direct connection to area 0 via the virtual link.

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MCQmedium

A network engineer is troubleshooting an OSPFv2 route flapping issue. The router R1 is learning a route to 192.168.1.0/24 via two different paths: one through R2 and one through R3. The route is flapping between the two paths every few seconds. 'show ip ospf interface' shows that both interfaces are stable. What is the most likely cause?

A.The routers R2 and R3 have the same OSPF router ID.

B.The route is being redistributed by both R2 and R3 with different metrics.

C.The OSPF network type on the interfaces is set to broadcast, causing DR/BDR instability.

D.The link between R1 and R2 has a high error rate causing intermittent packet loss.

AnswerA

Duplicate router IDs can cause OSPF to see the same route from two different neighbors as different, leading to route flapping.

Why this answer

Route flapping can be caused by a number of issues, but if the interfaces are stable, the problem is likely due to a routing loop or a metric issue. One common cause is that the routers are using the same router ID, causing OSPF to see the same route from two different neighbors as equal-cost paths, but the route may be flapping due to a change in the metric. Another cause is that the link between R1 and R2 is flapping at Layer 1, but the stem says the interfaces are stable.

The most likely cause is that the routers have duplicate router IDs, which can cause OSPF to treat the same route as two different routes and cause instability.

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MCQhard

A network engineer is troubleshooting OSPFv3 on a dual-stack network. Routers R1 and R2 are connected via a serial link. Both routers have OSPFv3 configured for IPv6. The engineer runs 'show ipv6 ospf neighbor' on R1 and sees R2 as FULL/DR. However, R1 cannot ping the IPv6 address of R2's loopback interface. 'show ipv6 route ospf' on R1 does not show any OSPF routes. What is the most likely cause?

A.The OSPFv3 process has 'no ipv6 unicast-routing' enabled globally.

B.The interface on R2 is configured as passive under OSPFv3.

C.The interface on R1 does not have an IPv6 address configured.

D.The OSPFv3 process is configured with 'default-information originate always' but no default route exists.

AnswerC

OSPFv3 requires an IPv6 address on the interface to advertise the connected prefix; without it, the router cannot originate a route for that link, and other routes may not be learned if the neighbor also lacks IPv6 addressing.

Why this answer

In OSPFv3, the network type on serial interfaces defaults to POINT-TO-POINT, but if the interface is configured as BROADCAST (e.g., using 'ipv6 ospf network broadcast'), a DR/BDR election occurs. However, the adjacency is FULL, so the issue is not adjacency. The lack of OSPF routes in the routing table suggests that the routes are not being installed.

One common reason is that OSPFv3 requires an IPv6 address on the interface, but the router may have an IPv4-only configuration or the interface may not have an IPv6 address. Another possibility is that the OSPFv3 process is not redistributing connected routes. The most likely cause is that the interface does not have an IPv6 address configured, which is required for OSPFv3 to advertise prefixes.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show ip ospf virtual-links Virtual Link OSPF_VL0 to router 10.1.1.3 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface GigabitEthernet0/0, Cost of using 10 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:08 Adjacency State FULL Based on this output, what can be concluded?

A.The virtual link is using area 0 as the transit area.

B.The virtual link is functioning correctly and the adjacency is full.

C.Router R1 is not receiving hello packets on the virtual link.

D.The virtual link has a cost of 1.

AnswerB

The state is FULL and the link is up, indicating proper operation.

Why this answer

The virtual link to router 10.1.1.3 is up and in FULL state. It is running as a demand circuit, which suppresses hello packets when the link is stable. The transit area is area 1.

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MCQhard

A large enterprise network is experiencing intermittent loss of connectivity to a subnet 10.10.10.0/24 from remote sites. Router R1 has the following relevant configuration: interface GigabitEthernet0/0 ip address 10.1.1.1 255.255.255.252 ip ospf 1 area 0 interface GigabitEthernet0/1 ip address 10.2.2.1 255.255.255.252 ip ospf 1 area 1 router ospf 1 area 1 range 10.10.0.0 255.255.248.0 Router R2 shows: show ip route 10.10.10.0 Routing entry for 10.10.8.0/21 Known via "ospf 1", distance 110, metric 20, type inter-area Last update from 10.1.1.2 on GigabitEthernet0/0, 00:05:32 ago What is the root cause?

A.The summary route 10.10.8.0/21 does not include 10.10.10.0/24; adjust the area range to 10.10.0.0/20.

B.The metric of 20 indicates a redistribution issue; check redistributed routes.

C.The OSPF network type on GigabitEthernet0/0 is causing adjacency issues; change to point-to-point.

D.The area 1 range command is misconfigured with the wrong area; it should be area 0.

AnswerA

The range 10.10.8.0/21 covers 10.10.8.0 to 10.10.15.255, missing 10.10.10.0/24. A /20 range would include it.

Why this answer

The route summarization on R1 for area 1 (10.10.0.0/21) includes 10.10.10.0/24, but the summary range is 10.10.8.0/21, which does not cover 10.10.10.0/24. This causes the specific route to be suppressed and not advertised, leading to loss of connectivity. The correct fix is to adjust the summary range to include the subnet.

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MCQeasy

Which OSPF packet type is used to send link-state advertisements (LSAs) and is acknowledged by the receiver?

A.Hello (type 1)

B.Database Description (type 2)

C.Link State Request (type 3)

D.Link State Update (type 4)

AnswerD

Correct. Link State Update packets carry LSAs and are acknowledged by the receiver.

Why this answer

OSPF packet type 4 is the Link State Update packet, used to flood LSAs. It is acknowledged by the receiver via a Link State Acknowledgment packet (type 5).

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MCQhard

A network engineer runs the following command to verify OSPF SPF calculations: R1# show ip ospf statistics OSPF Router with ID (1.1.1.1) (Process ID 1) Area 0: SPF algorithm executed 12 times SPF calculation time (in msec): Total: 12, Average: 1.0 Minimum: 0, Maximum: 2 Last SPF due to: LSA change Number of LSA changes: 5 Number of LSA deletions: 2 Number of LSA additions: 3 Number of LSA updates: 0 Area 1: SPF algorithm executed 3 times SPF calculation time (in msec): Total: 3, Average: 1.0 Minimum: 0, Maximum: 1 Last SPF due to: LSA change Number of LSA changes: 2 Number of LSA deletions: 0 Number of LSA additions: 2 Number of LSA updates: 0 What does this output indicate?

A.The router has not performed any SPF calculations.

B.Area 0 has experienced more network changes than Area 1, as indicated by higher SPF runs and LSA changes.

C.The SPF calculation time is too high, indicating a performance issue.

D.The last SPF was triggered by a timer expiry.

AnswerB

Area 0 has 12 SPF runs and 5 LSA changes, while Area 1 has 3 SPF runs and 2 LSA changes.

Why this answer

The output shows OSPF SPF statistics for multiple areas, including number of SPF runs and LSA changes.

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MCQmedium

Examine this OSPF configuration on router R5: router ospf 1 network 10.0.0.0 0.255.255.255 area 0 passive-interface default no passive-interface GigabitEthernet0/0 What is the effect of the passive-interface default command?

A.All interfaces except GigabitEthernet0/0 will be passive; GigabitEthernet0/0 will send and receive OSPF hellos.

B.All interfaces are passive, including GigabitEthernet0/0, because the no passive-interface command is ignored.

C.Only interfaces with network statements will be affected; other interfaces remain active.

D.The configuration is invalid because passive-interface default cannot be used with OSPF.

AnswerA

Correct. The default passive is overridden for GigabitEthernet0/0.

Why this answer

The passive-interface default command sets all interfaces as passive by default, meaning they will not send OSPF hello packets or form adjacencies. The no passive-interface command then overrides this for the specified interface, allowing it to form adjacencies.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show ipv6 ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/BDR 00:00:35 FE80::2 GigabitEthernet0/0 10.1.1.3 1 FULL/DR 00:00:32 FE80::3 GigabitEthernet0/1 Based on this output, which statement is correct regarding OSPFv3?

A.Router R1 is the DR on the segment connected to GigabitEthernet0/0.

B.Router R1 has a full adjacency with both neighbors in OSPFv3.

C.The OSPFv3 process is using IPv4 addresses as router IDs.

D.Router R1 is not receiving hello packets from 10.1.1.3.

AnswerB

Both neighbors show FULL state, indicating complete adjacency in OSPFv3.

Why this answer

The output shows OSPFv3 neighbors. The neighbor 10.1.1.2 is in state FULL/BDR, meaning it is the Backup Designated Router. The neighbor 10.1.1.3 is in state FULL/DR, meaning it is the Designated Router.

The addresses are link-local IPv6 addresses.

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MCQmedium

In OSPF, what is the default administrative distance for intra-area routes on a Cisco IOS-XE router?

A.90

B.110

C.115

D.120

AnswerB

Correct. OSPF uses a default administrative distance of 110 for all route types.

Why this answer

Cisco IOS-XE assigns an administrative distance of 110 to all OSPF routes, including intra-area, inter-area, and external routes, unless modified.

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MCQhard

In OSPFv3, which authentication method is supported by default?

A.MD5 authentication

B.Simple password authentication

C.IPsec authentication

D.No authentication is supported

AnswerC

Correct. OSPFv3 relies on IPsec for authentication and integrity.

Why this answer

OSPFv3 uses IPsec for authentication and encryption, as defined in RFC 4552. It does not support the simple password or MD5 authentication used in OSPFv2.

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Drag & Dropmedium

Drag and drop the steps to troubleshoot OSPF DR/BDR election on a multi-access segment into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

The correct order ensures that the OSPF DR/BDR election is properly influenced. First, verify the current DR/BDR roles using show ip ospf interface. Next, set the OSPF priority on the desired router to a higher value than the current DR.

Then, clear the OSPF process on all routers to force a new election. After that, verify the new DR/BDR roles have been elected as expected. Finally, confirm that adjacencies are formed with the new DR/BDR.

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Multi-Selectmedium

Which TWO statements about OSPFv3 (OSPF for IPv6) are true when comparing it to OSPFv2? (Choose TWO.)

Select 2 answers

A.OSPFv3 uses link-local IPv6 addresses for neighbor discovery.

B.OSPFv3 uses the same LSA types as OSPFv2.

C.OSPFv3 supports authentication using MD5 or SHA within the OSPF packet.

D.OSPFv3 uses the 'network' command to enable OSPF on interfaces.

E.OSPFv3 operates on a per-link basis rather than per-IP-subnet.

AnswersA, E

OSPFv3 routers form adjacencies using their link-local IPv6 addresses.

Why this answer

OSPFv3 runs on a per-link basis (not per-subnet) and uses link-local addresses for neighbor discovery. OSPFv3 still uses areas and LSAs, and authentication is handled by IPsec, not OSPF itself. OSPFv3 does not use the 'network' command; it uses 'ipv6 ospf' under the interface.

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MCQmedium

Which OSPF network type defaults to a hello interval of 30 seconds and a dead interval of 120 seconds on Cisco IOS?

A.Broadcast

B.Point-to-point

C.Non-Broadcast (NBMA)

D.Point-to-multipoint

AnswerC

Correct. NBMA network type defaults to hello interval 30 seconds and dead interval 120 seconds.

Why this answer

The Non-Broadcast Multi-Access (NBMA) network type uses a default hello interval of 30 seconds and a dead interval of 120 seconds, as per Cisco implementation.

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MCQmedium

A network engineer is troubleshooting OSPFv2 route redistribution. R1 is an ASBR redistributing static routes into OSPF. R2, an internal router, receives the redistributed routes but they appear as O E2 routes. However, R1 also has a directly connected network 10.1.1.0/24 that is not being advertised as an OSPF route. 'show ip ospf database external' on R2 shows the redistributed static routes but not the connected network. What is the most likely cause?

A.The connected network is not included in the redistribution because the engineer used 'redistribute static' without the 'subnets' keyword.

B.The connected network is not being advertised because it is not part of the OSPF process; the engineer must configure 'network 10.1.1.0 0.0.0.255 area 0' under router ospf.

C.The ASBR is missing the 'redistribute connected' command under the OSPF process.

D.The connected network is a loopback interface, and OSPF does not advertise loopback networks by default.

AnswerC

Without 'redistribute connected', the directly connected network is not advertised into OSPF, even if the interface is enabled for OSPF (which it may not be).

Why this answer

By default, OSPF does not redistribute connected routes unless explicitly configured. The ASBR must use the 'redistribute connected' command under the OSPF process to advertise directly connected networks. The static routes are being redistributed because they are matched by the 'redistribute static' command, but the connected network is not part of the static route set unless it is also a static route.

The engineer likely forgot to add 'redistribute connected' or use the 'subnets' keyword.

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MCQeasy

What is the default OSPF hello interval on a point-to-point serial interface?

A.10 seconds

B.30 seconds

C.40 seconds

D.20 seconds

AnswerA

Correct. Point-to-point and broadcast networks use a 10-second hello interval.

Why this answer

OSPF hello interval defaults are based on the network type. For point-to-point and broadcast networks, the default hello interval is 10 seconds. For NBMA and point-to-multipoint, it is 30 seconds.

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MCQhard

An engineer configures a distribute-list on an OSPF router to filter routes. However, the routes are still being advertised to neighbors. Which is the most likely explanation?

A.The distribute-list filters routes in the routing table, not the LSAs sent in OSPF updates.

B.The distribute-list is applied to the wrong interface.

C.The distribute-list uses an incorrect prefix-list.

D.The OSPF process needs to be restarted for the distribute-list to take effect.

AnswerA

Distribute-lists in OSPF only control which routes are installed in the local routing table, not which LSAs are advertised.

Why this answer

A distribute-list in OSPF filters routes in the inbound or outbound direction of the routing table, but it does not filter the actual LSA advertisements. OSPF uses LSAs to propagate routes; filtering with distribute-list only affects the local routing table, not the LSAs sent to neighbors.

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MCQmedium

Consider this OSPFv3 configuration on router R2: ipv6 router ospf 10 router-id 2.2.2.2 area 0 authentication ipsec spi 256 md5 1234567890abcdef1234567890abcdef interface GigabitEthernet0/0 ipv6 address 2001:db8:1::1/64 ipv6 ospf 10 area 0 What is the effect of this configuration?

A.OSPFv3 will use IPsec MD5 authentication for all packets in area 0, including on GigabitEthernet0/0.

B.Authentication is applied only to the GigabitEthernet0/0 interface, not the entire area.

C.The configuration is invalid because OSPFv3 does not support IPsec authentication.

D.The router-id is missing, so OSPFv3 will not start.

AnswerA

Correct. The area authentication command applies to all interfaces in that area.

Why this answer

The area authentication command under OSPFv3 enables IPsec authentication for the entire area. The interface is enabled for OSPFv3 in area 0, so it will use the area authentication. However, OSPFv3 authentication uses IPsec AH or ESP; the configuration shown is valid.

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MCQhard

An engineer configures OSPFv2 with a route-map to set the metric on redistributed routes. After redistribution, the metric is not being set as expected. Which is the most likely explanation?

A.The route-map does not have a match statement, so it applies to no routes.

B.The redistribution command uses the 'subnets' keyword, which overrides the route-map.

C.The route-map is applied to the wrong direction.

D.The OSPF process is configured with 'default-metric' command, which overrides the route-map.

AnswerA

Without a match statement, the route-map does not apply to any routes, and the default metric is used.

Why this answer

When redistributing routes into OSPF, the metric is set using the 'metric' keyword in the redistribution command or via a route-map. However, if the route-map does not explicitly match the routes, the default metric (20 for external type 2) is used. Additionally, if the route-map uses 'set metric' but the redistribution command also has a 'metric' keyword, the route-map overrides the redistribution command.

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MCQmedium

A network engineer runs the following command to troubleshoot OSPFv3 adjacency: R1# debug ipv6 ospf adj *Mar 1 00:15:23.456: OSPFv3-1-IPv6 ADJ Gi0/0: Rcv pkt from 2001:DB8:1::2, src 2001:DB8:1::2, area 0 *Mar 1 00:15:23.457: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Our address 2001:DB8:1::1, his address 2001:DB8:1::2 *Mar 1 00:15:23.458: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Neighbor is not DR, state 2WAY *Mar 1 00:15:23.459: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: DR is 2001:DB8:1::2, BDR is 2001:DB8:1::1 *Mar 1 00:15:23.460: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Build the Start DBD *Mar 1 00:15:23.462: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Master/Slave negotiation done *Mar 1 00:15:23.464: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Exchange done, loading started *Mar 1 00:15:23.466: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Loading done *Mar 1 00:15:23.468: OSPFv3-1-IPv6 ADJ Gi0/0: Nbr 2.2.2.2: Full What does this output indicate?

A.The OSPFv3 adjacency failed due to area mismatch.

B.The OSPFv3 adjacency formed successfully between routers with router IDs 1.1.1.1 and 2.2.2.2.

C.The adjacency is stuck in Exstart state due to interface MTU mismatch.

D.The router is the DR on this segment.

AnswerB

The debug shows the neighbor with router ID 2.2.2.2 and the adjacency reaching Full.

Why this answer

The debug output shows the successful OSPFv3 adjacency formation between two routers on interface Gi0/0.

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Drag & Dropmedium

Drag and drop the steps to verify and validate OSPF operational state into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

The verification process starts by checking the OSPF neighbor state with show ip ospf neighbor. Next, examine the OSPF database using show ip ospf database to see LSAs. Then, verify the routing table for OSPF routes with show ip route ospf.

After that, check interface-specific OSPF details with show ip ospf interface. Finally, test end-to-end connectivity with extended ping to validate reachability.

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MCQmedium

Consider this OSPF configuration on router R6: router ospf 1 network 10.0.0.0 0.255.255.255 area 0 area 0 stub What is the effect of the area 0 stub command?

A.Area 0 will become a stub area, blocking type 5 LSAs from entering the backbone.

B.The configuration is rejected by IOS because the backbone area cannot be a stub.

C.The command is ignored, and area 0 remains a normal area.

D.Only type 5 LSAs are blocked, but type 3 and 4 LSAs are still allowed.

AnswerB

Correct. RFC 2328 prohibits the backbone from being a stub.

Why this answer

The area 0 stub command is invalid because area 0 (the backbone) cannot be configured as a stub area. Stub areas are used to reduce LSA flooding, but the backbone must have full routing information. This configuration will be rejected by IOS.

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Multi-Selecthard

Which TWO statements about OSPFv2 authentication troubleshooting are true? (Choose TWO.)

Select 2 answers

A.The 'show ip ospf interface' command displays the authentication type and key ID configured on an interface.

B.The 'debug ip ospf adj' command can show authentication mismatch errors during neighbor adjacency formation.

C.OSPFv2 supports only MD5 authentication; SHA is not supported.

D.Plaintext authentication is the most secure method and is recommended for production networks.

E.The 'ip ospf authentication-key' command is used to configure SHA authentication.

AnswersA, B

Correct. The output of 'show ip ospf interface' includes fields like 'Auth' and 'Key ID' when authentication is configured.

Why this answer

OSPFv2 supports MD5 and SHA authentication, and the 'show ip ospf interface' command can verify authentication configuration. The 'debug ip ospf adj' command can reveal authentication failures. Plaintext authentication is supported but deprecated, and the 'area authentication' command is used for area-level configuration.

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MCQhard

An engineer configures OSPFv3 with multiple areas. On the ABR, routes from area 1 are not being advertised into area 0. Which is the most likely explanation?

A.The ABR does not have a direct interface in area 0.

B.The ABR has a higher router ID than the other routers.

C.The OSPFv3 process is configured with the 'no-redistribution' command.

D.The ABR is configured as a stub router.

AnswerA

An ABR must be directly connected to area 0 to advertise routes between areas.

Why this answer

OSPFv3 requires that the ABR have a direct connection to area 0. If the ABR is not directly connected to area 0, it will not advertise inter-area routes. Additionally, OSPFv3 uses the same rule as OSPFv2: an ABR must have at least one interface in area 0 to function as an ABR.

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Multi-Selecthard

An engineer is troubleshooting an OSPFv2 adjacency that remains stuck in EXSTART state. Which TWO actions should the engineer take to resolve the issue? (Choose TWO.)

Select 2 answers

A.Verify that the MTU on both interfaces is identical.

B.Ensure that the OSPF hello and dead intervals match on both routers.

C.Check that the OSPF network type is the same on both interfaces.

D.Confirm that the OSPF router IDs are unique across the network.

E.Increase the OSPF retransmit interval on both routers.

AnswersA, C

Correct. An MTU mismatch can prevent DD packets from being exchanged properly, causing the adjacency to stay in EXSTART.

Why this answer

An EXSTART state indicates a problem with the Database Description (DD) packet exchange, often due to MTU mismatch or mismatched interface MTU values. Also, mismatched OSPF network types can cause DD packet issues. The other options are either unrelated or incorrect.

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MCQhard

An engineer configures OSPFv2 on two routers with a direct Ethernet link. The routers are stuck in the EXSTART state. Which is the most likely explanation?

A.The interface MTU on one router is 1500, and on the other is 1400.

B.The OSPF hello and dead intervals are mismatched.

C.One router has OSPF authentication configured, and the other does not.

D.The OSPF network type is point-to-point on one router and broadcast on the other.

AnswerA

An MTU mismatch causes DBD packets to be dropped, stalling the adjacency in EXSTART.

Why this answer

OSPF neighbors can become stuck in EXSTART when there is a mismatch in the interface MTU. The DBD packet size is based on the interface MTU; if the receiving interface has a smaller MTU, the DBD packet is dropped, preventing the adjacency from progressing.

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MCQhard

VRF route leaking between two VRFs is causing unexpected reachability to a sensitive subnet. Router R1 has the following relevant configuration: vrf definition BLUE rd 100:1 ! address-family ipv4 route-target export 100:1 route-target import 100:2 vrf definition RED rd 100:2 ! address-family ipv4 route-target export 100:2 route-target import 100:1 interface GigabitEthernet0/0 vrf forwarding BLUE ip address 10.1.1.1 255.255.255.0 interface GigabitEthernet0/1 vrf forwarding RED ip address 10.2.2.1 255.255.255.0 router ospf 1 vrf BLUE network 10.1.1.0 0.0.0.255 area 0 router ospf 2 vrf RED network 10.2.2.0 0.0.0.255 area 0 A ping from a host in BLUE VRF to 10.2.2.2 (RED VRF) succeeds, but it should not. What is the root cause?

A.Route-target import/export is symmetric, causing full route exchange; use route-map to filter.

B.The OSPF process IDs are different; they should be the same for route leaking.

C.The network commands are missing the vrf keyword; add vrf BLUE/RED.

D.The interfaces are in the wrong VRF; move GigabitEthernet0/1 to BLUE.

AnswerA

Both VRFs import each other's routes, so all routes are leaked. Route-maps can restrict which prefixes are imported.

Why this answer

The route-target import/export configuration is bidirectional, causing full route leaking between VRFs. This allows hosts in BLUE to reach RED subnets. The correct fix is to use import/export only for specific prefixes or use route-maps to control leaking.

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MCQmedium

A network engineer runs the following command to troubleshoot OSPF neighbor states: R1# show ip ospf neighbor detail Neighbor 2.2.2.2, interface address 10.1.1.2 In the area 0 via interface GigabitEthernet0/0 Neighbor priority is 1, State is FULL, 6 state changes DR is 10.1.1.2, BDR is 10.1.1.1 Options is 0x42 (LLS, DC) LLS Options is 0x1 (LR) Dead timer due in 00:00:36 Neighbor is up for 00:12:34 Index 1/1/1 Retransmission queue length 0, number of retransmission 1 First 0x0(0)/0x0(0)/0x0(0) Next 0x0(0)/0x0(0)/0x0(0) Last retransmission scan length is 1, maximum is 1 Last retransmission scan time is 0 msec, maximum is 0 msec What does this output indicate?

A.The neighbor is in the 2WAY state and not fully adjacent.

B.The neighbor is the DR and the adjacency is fully established.

C.There is a retransmission queue issue causing packet loss.

D.The neighbor is not participating in DR/BDR election.

AnswerB

The DR is 10.1.1.2 (neighbor's address) and state is FULL.

Why this answer

The output shows detailed OSPF neighbor information, including state, DR/BDR roles, and timers.

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Drag & Drophard

Drag and drop the steps to troubleshoot OSPF adjacency or connectivity failures into the correct order, from first to last.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Why this order

Troubleshooting OSPF adjacency failures starts with verifying Layer 3 connectivity using ping. Next, check that OSPF is enabled on the correct interfaces with show ip ospf interface. Then, verify OSPF network type and area ID match on both sides.

After that, check for mismatched authentication settings. Finally, clear the OSPF process to reset adjacency attempts.

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MCQhard

A network engineer runs the following command on Router R1: R1# show ip ospf database OSPF Router with ID (10.1.1.1) (Process ID 1) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 10.1.1.1 10.1.1.1 120 0x80000002 0x00A1B2 3 10.1.1.2 10.1.1.2 200 0x80000001 0x00B2C3 2 10.1.1.3 10.1.1.3 150 0x80000003 0x00C3D4 4 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 192.168.12.2 10.1.1.2 180 0x80000001 0x00D4E5 Based on this output, what can be concluded?

A.Router R1 is the DR on the segment 192.168.12.0/24.

B.Router 10.1.1.2 is the DR on the segment 192.168.12.0/24.

C.Router 10.1.1.3 has the highest router ID.

D.There is a network LSA for every broadcast segment in area 0.

AnswerB

The net link state with Link ID 192.168.12.2 is advertised by 10.1.1.2, meaning it is the DR on that segment.

Why this answer

The database shows router link states for three routers and one net link state. The net link state is advertised by 10.1.1.2, indicating it is the DR on the segment 192.168.12.0/24. The absence of other net link states suggests only one broadcast segment exists.

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MCQhard

An engineer configures OSPFv3 with a filter-list on an ABR to filter prefixes. After configuration, the routes are still being advertised. Which is the most likely explanation?

A.The filter-list only filters inter-area prefixes, not external routes.

B.The filter-list is applied to the wrong area.

C.The filter-list uses an incorrect prefix-list.

D.The OSPFv3 process needs to be restarted.

AnswerA

Filter-list in OSPFv3 applies to type 3 LSAs only, not type 5 LSAs.

Why this answer

In OSPFv3, prefix filtering is done using the 'prefix-list' or 'filter-list' command under the area. However, the filter-list in OSPFv3 filters type 3 LSAs (inter-area prefixes) but not type 5 LSAs (external routes). If the routes being advertised are external, the filter-list will not affect them.

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Multi-Selecthard

Which TWO statements correctly describe the behavior of OSPFv3 when troubleshooting neighbor adjacency issues on a Cisco IOS-XE router? (Choose TWO.)

Select 2 answers

A.OSPFv3 neighbor adjacencies are formed using the link-local IPv6 address of the neighbor.

B.The OSPFv3 router ID is a 128-bit value derived from the highest loopback IPv6 address.

C.The 'ipv6 router ospf' command is used to enable OSPFv3 on an interface.

D.The 'show ipv6 ospf neighbor' command displays the link-local address of each neighbor.

E.OSPFv3 uses the network type configured under the OSPFv3 process globally, not per interface.

AnswersA, D

Correct. OSPFv3 uses IPv6 link-local addresses for neighbor discovery and adjacency formation, not global unicast addresses.

Why this answer

OSPFv3 uses link-local addresses for neighbor adjacency formation and relies on IPv6 link-local addresses for next-hop resolution. The router ID is still a 32-bit value, and the network type must be configured under the interface. The 'ipv6 ospf' command is used to enable OSPFv3 on an interface, not 'ipv6 router ospf'.

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MCQhard

A network engineer runs the following command on Router R1: R1# show ip ospf database router 10.1.1.2 OSPF Router with ID (10.1.1.1) (Process ID 1) Router Link States (Area 0) LS age: 150 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 10.1.1.2 Advertising Router: 10.1.1.2 LS Seq Number: 80000002 Checksum: 0x1234 Length: 48 Number of Links: 2 Link connected to: a Transit Network (Link ID) Designated Router address: 192.168.12.2 (Link Data) Router Interface address: 192.168.12.2 Number of TOS metrics: 0 TOS 0 Metrics: 10 Link connected to: a Stub Network (Link ID) Network/subnet number: 10.2.2.0 (Link Data) Network Mask: 255.255.255.0 Number of TOS metrics: 0 TOS 0 Metrics: 10 Based on this output, which statement is correct?

A.Router 10.1.1.2 is connected to a transit network and a stub network.

B.Router 10.1.1.2 is the DR on the transit network.

C.Router 10.1.1.2 has a cost of 20 to reach the stub network.

D.Router 10.1.1.2 is not advertising any external routes.

AnswerA

The LSA lists two links: one transit (to the DR) and one stub (10.2.2.0/24).

Why this answer

The router LSA from 10.1.1.2 shows two links: one transit network (to the DR address) and one stub network (10.2.2.0/24). The transit link indicates it is connected to a broadcast segment where it is the DR (since it lists its own interface address as DR address).

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MCQmedium

A network engineer is troubleshooting an OSPFv2 adjacency issue between two directly connected routers, R1 and R2, both running IOS-XE. The link is a point-to-point Ethernet link. The engineer issues 'show ip ospf neighbor' on R1 and sees no neighbors. 'show ip ospf interface GigabitEthernet0/0' on R1 shows 'Network Type BROADCAST', but the link is actually a point-to-point link. Both routers have 'ip ospf 1 area 0' configured on the interface. What is the most likely cause of the adjacency not forming?

A.The OSPF network type mismatch between the two routers (one is BROADCAST, the other is POINT-TO-POINT).

B.The routers have duplicate OSPF router IDs.

C.The interface is configured with 'ip ospf passive-interface'.

D.The OSPF process is not enabled globally; 'router ospf 1' is missing.

AnswerB

Duplicate router IDs prevent OSPF adjacency from forming; each router must have a unique router ID.

Why this answer

The default OSPF network type on Ethernet interfaces is BROADCAST, which requires a DR/BDR election and uses multicast 224.0.0.5 and 224.0.0.6. On a point-to-point link, if both routers do not agree on the network type, they may not form an adjacency because the hello packets are sent differently. However, since both are BROADCAST, they should form an adjacency.

The real issue is likely a mismatch in OSPF network type if one side is manually set to POINT-TO-POINT, but here both are BROADCAST. A more common cause is that the interface is administratively down or there is a Layer 1 issue, but the stem indicates the interface is up. Another common cause is that the router IDs are not configured, leading to OSPF not starting.

The most likely cause in this scenario is that the routers have duplicate router IDs, which prevents adjacency formation. The stem does not mention router IDs, so the best answer is that the engineer should check for duplicate router IDs.

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MCQmedium

Consider this OSPF configuration on router R4: router ospf 1 network 192.168.1.0 0.0.0.255 area 0 neighbor 10.0.0.2 What is the effect of the neighbor statement?

A.R4 will attempt to form an OSPF adjacency with 10.0.0.2 over any interface that can reach it.

B.The neighbor command is ignored because the network type is broadcast by default on Ethernet interfaces.

C.R4 will send unicast OSPF packets to 10.0.0.2, but only if the interface is in area 0.

D.The configuration is invalid because the neighbor command must include a priority.

AnswerB

Correct. On Ethernet, OSPF uses multicast discovery; the neighbor command is not needed and is ignored.

Why this answer

The neighbor command is used in OSPF for non-broadcast multi-access (NBMA) networks to manually specify neighbors. However, the interface used to reach 10.0.0.2 must be configured with the appropriate network type (e.g., point-to-multipoint or non-broadcast). If the network type is broadcast or point-to-point, the neighbor command is ignored.

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MCQmedium

Which OSPF LSA type is flooded only within the originating area and is used for loop prevention by describing the topology of the area?

A.Type 1 LSA (Router LSA)

B.Type 2 LSA (Network LSA)

C.Type 3 LSA (Summary LSA)

D.Type 4 LSA (ASBR Summary LSA)

AnswerA

Correct. Router LSAs are area-scoped and describe the router's interfaces and neighbors.

Why this answer

Type 1 Router LSAs describe the router's links and are flooded only within the area. They provide topology information for loop prevention within the area.

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MCQhard

DMVPN spoke-to-spoke tunnel is not forming between two spokes. Hub router R1 has the following relevant configuration: interface Tunnel0 ip address 10.0.0.1 255.255.255.0 ip nhrp network-id 1 ip nhrp map multicast dynamic ip ospf 1 area 0 tunnel source GigabitEthernet0/0 tunnel mode gre multipoint Spoke R2 shows: show dmvpn Legend: Attrb -> S: Static, D: Dynamic, I: Incomplete Interface: Tunnel0, IPv4 NHRP Details Type:Spoke, NHRP Peers: 1 # Ent Peer NBMA Addr Peer Tunnel Add State UpDn Tm Attrb 1 192.168.1.1 10.0.0.1 UP 00:10:00 D Spoke R3 shows similar, but no spoke-to-spoke tunnel. What is the root cause?

A.Missing ip nhrp redirect on hub and ip nhrp shortcut on spokes.

B.OSPF network type is broadcast; change to point-to-multipoint.

C.IPsec is not configured; DMVPN requires encryption.

D.The tunnel key is mismatched; configure tunnel key on all routers.

AnswerA

NHRP redirect triggers shortcut creation; without it, spokes always use hub.

Why this answer

Spoke-to-spoke tunnel requires NHRP redirect and shortcut route. Without ip nhrp redirect on hub and ip nhrp shortcut on spokes, traffic between spokes goes through hub. OSPF over DMVPN may also need mtu or ipsec issues.

The correct fix is to enable NHRP redirect on hub and shortcut on spokes.

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MCQmedium

A network engineer is troubleshooting an OSPFv2 adjacency issue between two routers connected via a VLAN trunk. R1 and R2 are in different VLANs but are connected through a Layer 2 switch. The engineer has configured 'ip ospf 1 area 0' on the subinterfaces. The adjacency forms but is stuck in INIT state. What is the most likely cause?

A.The routers have the same OSPF router ID.

B.The OSPF hello interval is mismatched between the two routers.

C.The subinterfaces are in different VLANs, preventing Layer 2 communication.

D.The OSPF network type is set to point-to-point on one side and broadcast on the other.

AnswerA

When a router receives a hello packet with its own router ID, it ignores it, causing the adjacency to stay in INIT.

Why this answer

The INIT state indicates that the router has received a hello packet from the neighbor but the neighbor has not seen its own router ID in the hello packet. This is often due to a mismatch in the OSPF network type or a unicast communication issue. In a VLAN trunk scenario, if the subinterfaces are not in the same VLAN, the routers may not be able to communicate at Layer 2.

However, the most common cause is that the routers are using the same router ID, which causes the hello packet to be ignored because the router sees its own router ID in the neighbor list.

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MCQhard

A network engineer notices that routes redistributed from EIGRP into OSPF are causing routing loops. Router R1 has the following relevant configuration: router eigrp 100 redistribute ospf 1 metric 10000 100 255 1 1500 router ospf 1 redistribute eigrp 100 subnets metric-type 1 Router R2 shows: show ip route 192.168.1.0 Routing entry for 192.168.1.0/24 Known via "ospf 1", distance 110, metric 20, type E1 Last update from 10.1.1.1, 00:01:30 ago Also, R2 has a default route via R1. What is the root cause?

A.Mutual redistribution without filtering causes a routing loop; apply distribute-list or route-map with tags.

B.The metric-type 1 should be type 2 to avoid loops.

C.The EIGRP metric values are incorrect; they should match OSPF cost.

D.The subnets keyword is missing in the redistribute command for OSPF.

AnswerA

Without filtering, routes are redistributed back and forth, creating loops. Tags and filters break the cycle.

Why this answer

The mutual redistribution between EIGRP and OSPF without route filtering can cause a routing loop. R1 redistributes OSPF into EIGRP, and EIGRP back into OSPF, creating a feedback loop. The E1 metric of 20 suggests the route was redistributed twice.

The correct fix is to implement route tagging and filtering to prevent loop.

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MCQmedium

Examine this OSPF configuration snippet on router R3: router ospf 1 network 10.1.1.0 0.0.0.255 area 0 default-information originate always What is the effect of the default-information originate always command?

A.R3 will advertise a default route into OSPF only if it has a default route in its routing table.

B.R3 will unconditionally advertise a default route into OSPF as an external LSA type 5.

C.R3 will advertise a default route only if it is an ASBR.

D.The command is invalid because default-information originate requires a route-map.

AnswerB

Correct. The 'always' keyword forces advertisement regardless of the presence of a default route.

Why this answer

The command injects a default route (0.0.0.0/0) into the OSPF domain as an external LSA type 5, regardless of whether the router has a default route in its routing table. The 'always' keyword forces advertisement even without a default route.

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MCQmedium

A network engineer runs the following command to troubleshoot an OSPF adjacency issue: R1# debug ip ospf adj *Mar 1 00:12:34.567: OSPF-1 ADJ RtrA: Interface GigabitEthernet0/0 going Up *Mar 1 00:12:34.568: OSPF-1 ADJ RtrA: 2 Way Communication to 10.1.1.2 on GigabitEthernet0/0, state 2WAY *Mar 1 00:12:34.570: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Our router ID 1.1.1.1, his router ID 2.2.2.2 *Mar 1 00:12:34.571: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Neighbor is not DR, state 2WAY *Mar 1 00:12:34.572: OSPF-1 ADJ RtrA: NBR 10.1.1.2: DR is 10.1.1.2, BDR is 10.1.1.1 *Mar 1 00:12:34.573: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Build the Start DBD *Mar 1 00:12:34.574: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Master/Slave negotiation done *Mar 1 00:12:34.576: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Exchange done, loading started *Mar 1 00:12:34.578: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Loading done *Mar 1 00:12:34.580: OSPF-1 ADJ RtrA: NBR 10.1.1.2: Full What does this output indicate?

A.The adjacency failed due to a mismatch in the DR election.

B.The adjacency formed successfully, and the neighbor is in Full state.

C.The adjacency is stuck in Exstart state due to MTU mismatch.

D.The neighbor is not the DR, so the adjacency will not form.

AnswerB

The sequence of messages shows all OSPF adjacency steps completing, ending with 'Full'.

Why this answer

The debug output shows the complete OSPF adjacency formation process from Down to Full state, indicating a successful adjacency.

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MCQmedium

A network engineer runs the following command on Router R1: R1# show ip ospf interface GigabitEthernet0/0 GigabitEthernet0/0 is up, line protocol is up Internet Address 192.168.12.1/24, Area 0 Process ID 1, Router ID 10.1.1.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State BDR, Priority 1 Designated Router (ID) 10.1.1.2, Interface address 192.168.12.2 Backup Designated router (ID) 10.1.1.1, Interface address 192.168.12.1 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 oob-resync timeout 40 Hello due in 00:00:03 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 10.1.1.2 (Designated Router) Suppress hello for 0 neighbor(s) Based on this output, which statement is correct?

A.Router R1 is the Designated Router on this segment.

B.Router R1 has a priority of 0, preventing it from becoming DR.

C.The dead timer is set to 40 seconds and is functioning correctly.

D.Router R1 is not receiving hello packets from the DR.

AnswerC

The dead interval is 40 seconds, and the hello timer is 10 seconds, which is standard. The adjacency is up, so timers are working.

Why this answer

The interface is in state BDR, meaning Router R1 is the backup designated router. The DR is 10.1.1.2. The output shows one neighbor, which is the DR, and the adjacency is full.

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MCQmedium

Which LSA type is used by OSPF to advertise prefixes from other routing protocols (redistribution) and has a default metric of 20?

A.Type 1 LSA (Router LSA)

B.Type 3 LSA (Summary LSA)

C.Type 4 LSA (ASBR Summary LSA)

D.Type 5 LSA (AS-external LSA)

AnswerD

Correct. Type 5 LSAs carry external routes with a default metric of 20.

Why this answer

Type 5 AS-external LSAs are used to advertise external routes redistributed into OSPF. The default metric for these LSAs is 20, as defined by Cisco IOS.

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