How many OSPF Troubleshooting Scenarios questions are on this page?

This page has 15 OSPF Troubleshooting Scenarios scenario questions for the 350-401 exam, each with detailed explanations and wrong-answer analysis.

How should I approach 350-401 scenario questions?

Read the full scenario before looking at the answer options. Identify the constraint or requirement in the scenario, then eliminate options that are generally true but wrong for this specific case. Scenario questions reward careful reading over pattern matching.

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Scenario-based practice

OSPF Troubleshooting Scenarios

Practise 350-401 ENCOR 350-401 OSPF questions covering neighbour states, router IDs, areas, timers, passive interfaces, OSPF cost, route selection, and command-output troubleshooting.

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scenario questions

350-401

exam code

Cisco

vendor

Scenario guide

How to approach ospf troubleshooting scenarios

OSPF neighbour adjacencies, route advertisements, and DR/BDR elections appear consistently on the CCNA. These questions test whether you can read OSPF state from show commands and identify why two routers fail to reach FULL adjacency or why a route isn't being learned.

Quick answer

OSPF questions usually test neighbour formation, areas, router IDs, route preference, metrics and command-output interpretation.

How OSPF neighbours form and why adjacency can fail.

How router ID, area ID, timers, passive interfaces and authentication affect OSPF.

How OSPF cost influences route selection.

How to read show ip route and show ip ospf neighbor output.

Practice scenarios

Question 1mediumdrag order

Review the full OSPF breakdown →

Drag and drop the steps of OSPF summarization at ABR configuration steps 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

Question 2mediummatching

Review the full OSPF breakdown →

Drag and drop each OSPF router role on the left to its matching function on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Generates the Network LSA and maintains full adjacencies with all routers on the segment

Monitors the DR and assumes the DR role if the DR fails

Forms full adjacencies only with the DR and BDR

Connects multiple areas and advertises inter-area routes

Redistributes external routes into OSPF

Question 3mediummultiple choice

Review the full OSPF breakdown →

Given the following configuration on a Cisco IOS-XE device:

router ospf 1
 network 10.0.0.0 0.255.255.255 area 0

interface GigabitEthernet0/0
 ip address 10.1.1.1 255.255.255.0
 ip ospf cost 10

interface GigabitEthernet0/1
 ip address 10.2.2.1 255.255.255.0

Which statement is true about OSPF operation?

A
Both interfaces will have an OSPF cost of 10.
Why wrong: Incorrect. Only GigabitEthernet0/0 has the explicit cost of 10. GigabitEthernet0/1 will use the default cost based on its bandwidth (e.g., 1 for GigabitEthernet).
B
GigabitEthernet0/0 will have an OSPF cost of 10, and GigabitEthernet0/1 will have a default cost based on its bandwidth.
Correct. The explicit cost applies only to the interface it is configured on. The other interface uses the default cost.
C
Both interfaces will have the same OSPF cost because they are in the same area.
Why wrong: Incorrect. OSPF cost is interface-specific and not determined by area membership alone.
D
OSPF will not run on either interface because the network command uses a wildcard mask of 0.255.255.255.
Why wrong: Incorrect. The wildcard mask 0.255.255.255 matches all addresses starting with 10.x.x.x, so both interfaces are included.

Full breakdown with real-world context →

Question 4mediummultiple choice

Study the full EIGRP explanation →

Examine the following EIGRP configuration on a Cisco IOS-XE device:

router eigrp 100
 network 10.0.0.0 0.255.255.255
 passive-interface default
 no passive-interface GigabitEthernet0/0

interface GigabitEthernet0/0
 ip address 10.1.1.1 255.255.255.0

interface GigabitEthernet0/1
 ip address 10.2.2.1 255.255.255.0

Which statement is true?

A
EIGRP will form adjacencies on both GigabitEthernet0/0 and GigabitEthernet0/1.
Why wrong: Incorrect. Only GigabitEthernet0/0 is explicitly set to not be passive. GigabitEthernet0/1 remains passive and will not form adjacencies.
B
EIGRP will form an adjacency only on GigabitEthernet0/0.
Correct. GigabitEthernet0/0 is not passive, so it will send and receive hellos. GigabitEthernet0/1 is passive by default.
C
EIGRP will not form any adjacencies because the network command does not match the interface subnets.
Why wrong: Incorrect. The network 10.0.0.0 0.255.255.255 matches both interfaces (10.1.1.1 and 10.2.2.1).
D
EIGRP will form adjacencies on all interfaces except those with 'passive-interface' configured.
Why wrong: Incorrect. The 'passive-interface default' makes all interfaces passive unless overridden with 'no passive-interface'.

Full breakdown with real-world context →

Question 5mediumdrag order

Review the full OSPF breakdown →

Drag and drop the steps of OSPF neighbor adjacency formation 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

Question 6mediumdrag order

Review the full OSPF breakdown →

Drag and drop the steps of OSPF SPF calculation steps (Dijkstra) 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

Question 7mediummulti select

Review the full OSPF breakdown →

Which two statements about OSPF network types are true? (Choose two.)

A
On a broadcast multiaccess network, OSPF elects a DR and BDR to reduce LSA flooding.
Correct because on broadcast networks (e.g., Ethernet), a Designated Router (DR) and Backup DR are elected to minimize the number of adjacencies and flooding.
B
The OSPF point-to-point network type requires a DR/BDR election.
Why wrong: Incorrect because point-to-point networks do not use DR/BDR; they form a single adjacency between the two routers.
C
On a non-broadcast multiaccess (NBMA) network, OSPF can use the neighbor command to manually discover neighbors.
Correct because NBMA networks (e.g., Frame Relay) require manual neighbor configuration since they lack broadcast capability.
D
The OSPF point-to-multipoint network type always elects a DR.
Why wrong: Incorrect because point-to-multipoint networks treat each link as a point-to-point link and do not use DR/BDR.
E
The default OSPF network type for a loopback interface is point-to-point.
Why wrong: Incorrect because the default network type for a loopback interface is 'loopback', which is a special type that always advertises the interface as a /32 host route.

Full breakdown with real-world context →

Question 8mediumdrag order

Review the full OSPF breakdown →

Drag and drop the steps of EIGRP redistribution from OSPF with metric seeding 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

Question 9mediumdrag order

Review the full OSPF breakdown →

Drag and drop the steps of OSPF redistribution from EIGRP with metric conversion 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

Question 10hardmultiple choice

Review the full OSPF breakdown →

A network engineer issues the following command on Router R4:

R4# show ip ospf database

OSPF Router with ID (4.4.4.4) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count

1.1.1.1         1.1.1.1         123         0x80000002 0x00A1B2 2
2.2.2.2         2.2.2.2         456         0x80000003 0x00B2C3 3
4.4.4.4         4.4.4.4         789         0x80000001 0x00C3D4 1

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum

192.168.1.2     2.2.2.2         234         0x80000001 0x00D4E5

Based on this output, what can be concluded?

A
Router 2.2.2.2 is the Designated Router on the segment 192.168.1.0/24.
The Net Link State is originated by the DR, and the ADV Router is 2.2.2.2, so it is the DR.
B
Router 1.1.1.1 has three OSPF-enabled interfaces.
Why wrong: The link count for 1.1.1.1 is 2, not 3.
C
Router 4.4.4.4 is the BDR on the segment.
Why wrong: The BDR is not indicated in the database; the Net Link State is only from the DR.
D
There are multiple broadcast segments in area 0.
Why wrong: Only one Net Link State is listed, suggesting one broadcast segment.

Full breakdown with real-world context →

Question 11mediummulti select

Review the full OSPF breakdown →

Which two statements about OSPF network types are true? (Choose two.)

A
The point-to-point network type does not require a DR/BDR election.
Correct because in point-to-point networks, there are only two routers, so no DR/BDR is needed.
B
The broadcast network type uses a DR/BDR to reduce the number of adjacencies.
Correct because on broadcast multiaccess networks, a DR/BDR is elected to minimize adjacency formation and LSA flooding.
C
The NBMA network type automatically discovers neighbors via hello packets.
Why wrong: Incorrect because NBMA networks require manual neighbor configuration; they do not support dynamic neighbor discovery.
D
The point-to-multipoint network type requires a DR/BDR election.
Why wrong: Incorrect because point-to-multipoint treats each link as a point-to-point link and does not use DR/BDR.
E
The loopback interface defaults to the point-to-point network type.
Why wrong: Incorrect because the loopback interface defaults to the loopback network type, which is treated as a stub host.

Full breakdown with real-world context →

Question 12mediummulti select

Review the full OSPF breakdown →

Which two statements about OSPF neighbor states are true? (Choose two.)

A
The 2-Way state indicates that the router has received a Hello packet from the neighbor with its own Router ID in the neighbor list.
Correct because 2-Way state confirms bidirectional communication: each router sees its own Router ID in the other's Hello packet.
B
In the ExStart state, routers exchange Database Description (DBD) packets to describe their LSDB contents.
Why wrong: Incorrect because DBD exchange occurs in the Exchange state, not ExStart. ExStart is used to establish the master/slave relationship and initial DBD sequence numbers.
C
The Full state means the routers have synchronized their link-state databases and are fully adjacent.
Correct because Full is the final adjacency state, indicating that the LSDBs are fully synchronized between the two routers.
D
The Loading state occurs before the Exchange state in the neighbor state machine.
Why wrong: Incorrect because Loading occurs after Exchange. In Loading, routers send Link-State Requests for missing LSAs identified during the Exchange state.
E
The Down state means the router has received a Hello packet from the neighbor but has not yet established two-way communication.
Why wrong: Incorrect because Down means no Hello packets have been received from the neighbor. The Init state occurs when a Hello packet is received but two-way is not yet established.

Full breakdown with real-world context →

Question 13mediummatching

Review the full OSPF breakdown →

Drag and drop each OSPF network type on the left to its matching DR election behavior on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Elects DR and BDR; uses multicast Hello to 224.0.0.5

Elects DR and BDR; uses unicast Hello to configured neighbors

No DR/BDR election; uses multicast 224.0.0.5

Always advertised as a /32 host route; no DR election

Question 14harddrag order

Review the full OSPF breakdown →

Drag and drop the steps of OSPF route redistribution into a different autonomous system 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

Question 15mediummatching

Review the full OSPF breakdown →

Drag and drop each OSPF LSA type on the left to its matching description on the right.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts

Matches

Describes a router's directly attached links and interfaces

Generated by the DR to list all routers on a multiaccess segment

Advertises inter-area prefixes between areas

Advertises the location of an ASBR to other areas

Advertises external routes redistributed into OSPF

These 350-401 practice questions are part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style 350-401 questions with detailed explanations, topic-based practice, mock exams, readiness tracking, and study analytics.

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How to approach ospf troubleshooting scenarios

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Practice scenarios

Drag and drop the steps of OSPF summarization at ABR configuration steps into the correct order, from first to last.

Drag and drop each OSPF router role on the left to its matching function on the right.

Drag and drop the steps of OSPF neighbor adjacency formation into the correct order, from first to last.

Drag and drop the steps of OSPF SPF calculation steps (Dijkstra) into the correct order, from first to last.

Which two statements about OSPF network types are true? (Choose two.)

Drag and drop the steps of EIGRP redistribution from OSPF with metric seeding into the correct order, from first to last.

Drag and drop the steps of OSPF redistribution from EIGRP with metric conversion into the correct order, from first to last.

Which two statements about OSPF network types are true? (Choose two.)

Which two statements about OSPF neighbor states are true? (Choose two.)

Drag and drop each OSPF network type on the left to its matching DR election behavior on the right.

Drag and drop the steps of OSPF route redistribution into a different autonomous system into the correct order, from first to last.

Drag and drop each OSPF LSA type on the left to its matching description on the right.