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This page has 11 OSPF Troubleshooting Scenarios scenario questions for the 350-601 exam, each with detailed explanations and wrong-answer analysis.

How should I approach 350-601 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 350-601 Cisco DCCOR / CCNP Data Center Core 350-601 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

350-601

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 1mediummultiple choice

Review the full OSPF breakdown →

During a network upgrade, an engineer applies a new OSPF configuration on a Nexus 9000 spine. After the change, several leaf switches lose connectivity to each other. The engineer examines the logs and sees OSPF adjacency flapping. What is the most likely cause?

A
Duplicate router IDs.
Duplicate router IDs cause OSPF neighbors to flap.
B
OSPF hello timer mismatch.
Why wrong: Hello timer mismatch would prevent adjacency from forming.
C
MTU mismatch on the fabric links.
Why wrong: MTU mismatch can cause problems but not typically flapping.
D
Incorrect area configuration.
Why wrong: Incorrect area would prevent adjacency entirely.

Full breakdown with real-world context →

Question 2mediummultiple choice

Review the full OSPF breakdown →

An engineer is designing a Layer 3 network for a data center using OSPF. The core switches are connected to aggregation switches. To optimize convergence, which OSPF network type should be used on the links between core and aggregation?

A
broadcast
Why wrong: Default type but adds DR election overhead.
B
non-broadcast
Why wrong: Requires manual neighbor commands, not recommended for simple links.
C
point-to-multipoint
Why wrong: Used for hub-and-spoke topologies, not direct links.
D
point-to-point
Eliminates DR election, reduces convergence time.

Full breakdown with real-world context →

Question 3mediumdrag order

Review the full OSPF breakdown →

Sequence the steps for configuring OSPF on a Cisco Nexus switch in a data center fabric.

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

A
First, create the OSPF process with 'router ospf <process-id>'. Second, configure the router ID with 'router-id <id>'. Third, enable OSPF on interfaces using 'ip router ospf <process-id> area <area-id>'. Finally, verify with 'show ip ospf'.
This is the correct order because the OSPF process must exist before setting the router ID, and the router ID is needed before enabling OSPF on interfaces; verification is the final step.
B
First, configure the router ID before creating the OSPF process, then create the process, then enable on interfaces, then verify.
Why wrong: This is incorrect because setting the router ID requires an existing OSPF process; otherwise the command fails or is ignored.
C
First, create the OSPF process, then enable OSPF on interfaces, then configure the router ID, then verify.
Why wrong: This is incorrect because enabling OSPF on interfaces before setting the router ID may result in a dynamically assigned router ID, which is not deterministic and may change after reload.
D
First, enable OSPF on interfaces, then create the OSPF process, then set router ID, then verify.
Why wrong: This is incorrect because OSPF cannot be enabled on interfaces if the OSPF process does not exist yet.

Full breakdown with real-world context →

Question 4hardmultiple choice

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A Nexus switch experiences high CPU utilization due to excessive ICMP traffic. An engineer applies a CoPP policy that includes a class matching ICMP with a drop action. After applying, legitimate OSPF hello packets are also being dropped. What is the most likely cause?

A
The CoPP policy is applied to the wrong interface
Why wrong: CoPP is applied to the control plane, not an interface, so incorrect application is unlikely.
B
The CoPP policy rate-limits all traffic including OSPF below its needed rate
Why wrong: Rate-limiting would still allow some packets; complete dropping of OSPF indicates a drop action, not rate-limit exceed.
C
OSPF packets match the default class which has a drop action
If the default class action is drop, any traffic not explicitly matched (including OSPF) will be dropped. This is a common misconfiguration.
D
The class-map matches multiple protocols including OSPF
Why wrong: If the class-map explicitly matches ICMP via protocol or ACL, it should not match OSPF. However, a poorly designed ACL could cause this.

Full breakdown with real-world context →

Question 5mediummultiple choice

Review the full OSPF breakdown →

An engineer is configuring OSPF on a Cisco Nexus switch in a data center. The network consists of multiple point-to-point links. To improve convergence, the engineer wants to reduce the dead interval to 10 seconds. Which command sets the dead interval correctly?

A
ip ospf dead-interval 30
Why wrong: 30 is not 10.
B
ip ospf hello-interval 10
Why wrong: Sets hello interval, not dead.
C
ip ospf dead-interval 10
Sets dead interval to 10 seconds.
D
ip ospf dead-interval 40
Why wrong: 40 is default, not 10.

Full breakdown with real-world context →

Question 6easymultiple choice

Review the full OSPF breakdown →

A network engineer is configuring OSPF on a pair of Nexus 9000 switches acting as spine switches in a VXLAN fabric. The engineer needs to ensure that the spine switches do not become the DR for any VLAN. Which configuration should be applied?

A
Configure passive-interface default under OSPF.
Why wrong: Passive interface suppresses OSPF adjacencies, not DR election.
B
Set ospf network type to point-to-multipoint.
Why wrong: Point-to-multipoint still elects DRs in some scenarios.
C
Set ospf priority to 0 on the spine interfaces.
OSPF priority 0 prevents the router from participating in DR/BDR election.
D
Set ospf priority to 255 on the spine interfaces.
Why wrong: Priority 255 increases the chance of becoming DR.

Full breakdown with real-world context →

Question 7mediummultiple choice

Review the full OSPF breakdown →

An engineer is configuring OSPF on a Nexus 9000 switch in a data center spine-leaf topology. Which OSPF network type is most appropriate on the point-to-point links between leaf and spine switches to ensure fast convergence?

A
broadcast
Why wrong: Broadcast requires DR/BDR election and is slower on point-to-point links.
B
point-to-multipoint
Why wrong: Point-to-multipoint is used when one interface connects to multiple, not for direct spine-leaf.
C
point-to-point
Point-to-point is optimal for direct links, avoids DR/BDR.
D
non-broadcast
Why wrong: Non-broadcast is used for NBMA networks, not point-to-point.

Full breakdown with real-world context →

Question 8mediummultiple choice

Review the full OSPF breakdown →

Refer to the exhibit. An engineer configured a VXLAN tunnel endpoint (VTEP) but the VXLAN tunnel is not operational. The underlay OSPF adjacency is established. What is the missing configuration?

Exhibit

interface nve1
 source-interface loopback0
 member vni 10000 mcast-group 239.1.1.1
!
interface loopback0
 ip address 10.10.10.1 255.255.255.255
!
interface Ethernet1/1
 no switchport
 ip address 192.168.1.1 255.255.255.0
 ip router ospf 1 area 0

A
The NVE interface must be enabled with the no shutdown command.
Why wrong: NVE interfaces are usually administratively up by default; no shutdown is not typically required.
B
The multicast group must be reachable via the underlay.
Why wrong: Multicast reachability affects BUM traffic but not the tunnel's operational status.
C
The loopback0 interface is not included in the OSPF process.
The loopback0 interface, used as the NVE source, is not advertised via OSPF, so its IP is unreachable from other VTEPs.
D
The VNI must be mapped to a VLAN.
Why wrong: VNI-to-VLAN mapping is needed for Layer 2 forwarding, but the immediate issue is the unreachable source interface.

Full breakdown with real-world context →

Question 9mediummultiple choice

Review the full OSPF breakdown →

A network engineer is troubleshooting an OSPF adjacency issue between two Nexus switches. The neighbors are stuck in the EXSTART state. What is the most likely cause?

A
Hold timer mismatch
Why wrong: Hold timer mismatch causes adjacency to go down, not stuck in EXSTART.
B
Incorrect area ID
Why wrong: Area ID mismatch prevents neighbor discovery, not EXSTART.
C
MTU mismatch
MTU mismatch leads to DBD packet rejection, keeping the neighbor in EXSTART.
D
Duplicate router ID
Why wrong: Duplicate router IDs prevent adjacency formation entirely, not just EXSTART.

Full breakdown with real-world context →

Question 10mediummultiple choice

Review the full OSPF breakdown →

A network engineer is configuring OSPF on a Nexus switch. To ensure fast convergence in case of a link failure, which OSPF feature should be enabled?

A
OSPF authentication
Why wrong: Authentication secures OSPF but does not improve convergence.
B
OSPF Fast Hello
Fast Hello allows sub-second hello intervals for faster failure detection.
C
OSPF stub area
Why wrong: Stub areas reduce LSDB size but do not directly speed convergence.
D
OSPF route summarization
Why wrong: Summarization reduces routing table size but not convergence time.

Full breakdown with real-world context →

Question 11easymultiple choice

Review the full OSPF breakdown →

A network engineer is configuring OSPF on a Cisco Nexus switch for a data center network. The requirement is to ensure that the switch does not become the Designated Router (DR) on a multi-access segment. Which OSPF configuration achieves this?

A
Set OSPF priority to 255 on the interface
Why wrong: Priority 255 increases the chance of becoming DR.
B
Set OSPF priority to 0 on the interface
Priority 0 means the router will never become DR or BDR.
C
Change the OSPF network type to point-to-point
Why wrong: Point-to-point network type eliminates DR election, but it changes the behavior for all routers; the question asks specifically to prevent this switch from becoming DR.
D
Configure the interface as passive under OSPF
Why wrong: Passive interface suppresses OSPF hellos, so no adjacency is formed; it does not prevent DR election if hellos are sent.

Full breakdown with real-world context →

These 350-601 practice questions are part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style 350-601 questions with detailed explanations, topic-based practice, mock exams, readiness tracking, and study analytics.

OSPF Troubleshooting Scenarios

How to approach ospf troubleshooting scenarios

Quick answer

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Practice scenarios

During a network upgrade, an engineer applies a new OSPF configuration on a Nexus 9000 spine. After the change, several leaf switches lose connectivity to each other. The engineer examines the logs and sees OSPF adjacency flapping. What is the most likely cause?

An engineer is designing a Layer 3 network for a data center using OSPF. The core switches are connected to aggregation switches. To optimize convergence, which OSPF network type should be used on the links between core and aggregation?

Sequence the steps for configuring OSPF on a Cisco Nexus switch in a data center fabric.

A Nexus switch experiences high CPU utilization due to excessive ICMP traffic. An engineer applies a CoPP policy that includes a class matching ICMP with a drop action. After applying, legitimate OSPF hello packets are also being dropped. What is the most likely cause?

An engineer is configuring OSPF on a Cisco Nexus switch in a data center. The network consists of multiple point-to-point links. To improve convergence, the engineer wants to reduce the dead interval to 10 seconds. Which command sets the dead interval correctly?

A network engineer is configuring OSPF on a pair of Nexus 9000 switches acting as spine switches in a VXLAN fabric. The engineer needs to ensure that the spine switches do not become the DR for any VLAN. Which configuration should be applied?

An engineer is configuring OSPF on a Nexus 9000 switch in a data center spine-leaf topology. Which OSPF network type is most appropriate on the point-to-point links between leaf and spine switches to ensure fast convergence?

Refer to the exhibit. An engineer configured a VXLAN tunnel endpoint (VTEP) but the VXLAN tunnel is not operational. The underlay OSPF adjacency is established. What is the missing configuration?

Exhibit

A network engineer is troubleshooting an OSPF adjacency issue between two Nexus switches. The neighbors are stuck in the EXSTART state. What is the most likely cause?

A network engineer is configuring OSPF on a Nexus switch. To ensure fast convergence in case of a link failure, which OSPF feature should be enabled?

A network engineer is configuring OSPF on a Cisco Nexus switch for a data center network. The requirement is to ensure that the switch does not become the Designated Router (DR) on a multi-access segment. Which OSPF configuration achieves this?