CCNP Infrastructure Practice Question
A network engineer is deploying a new branch office with a Cisco Catalyst 9300 switch. The switch must participate in the corporate OSPF domain but must not become a designated router (DR) or backup designated router (BDR) on any broadcast segment. Which configuration should the engineer apply to the switch's OSPF interface?
⚠ Common exam trap
The trap here is assuming that any OSPF interface setting that alters adjacency behavior, such as changing the network type, will also prevent DR/BDR election without side effects.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ip ospf priority 0
The OSPF interface priority determines which routers are eligible to become DR or BDR on a broadcast or non-broadcast multi-access segment. A priority of 0 makes the router ineligible for these roles, so it will remain a DROTHER regardless of its router ID. This is the correct way to ensure the switch never becomes DR or BDR while still participating in OSPF.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ip ospf priority 0
Why this is correct
Setting the OSPF interface priority to 0 makes the router ineligible to become DR or BDR on that broadcast segment. The priority value is carried in Hello packets and used in the DR election; a priority of 0 explicitly excludes the interface from the election, ensuring the switch remains a DROTHER and only forms adjacencies with the DR and BDR.
- ✗
ip ospf network point-to-point
Why it's wrong here
Changing the OSPF network type to point-to-point eliminates the DR/BDR election on that interface, but it also changes the adjacency behavior and is intended for links connecting exactly two routers. On a multi-access segment with multiple OSPF speakers, this setting would not be appropriate and could disrupt neighbor relationships.
- ✗
ip ospf database-filter all out
Why it's wrong here
This command filters out outgoing LSAs on the interface, which can reduce flooding but does not prevent the router from becoming DR or BDR. The election is based on priority and router ID, not on LSA filtering. This would not satisfy the requirement and could cause database inconsistencies.
- ✗
ip ospf cost 65535
Why it's wrong here
Modifying the OSPF cost affects path selection for routing but has no impact on DR/BDR election. The router would still participate in the election and could become DR or BDR based on priority and router ID. The cost value is used in SPF calculations, not in the election process.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
About these practice questions
This 350-401 question is part of Courseiva's 1,923-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.