300-410 Layer 3 Technologies Practice Question
A network engineer is configuring OSPF on a Cisco router. The router has three interfaces in Area 0, and the engineer wants to ensure that the router does not become a Designated Router (DR) on any of these interfaces. Which command should be used on each interface?
⚠ Common exam trap
Candidates often confuse OSPF priority with other routing protocol metrics or assuming that a non-existent command like 'dr-disable' exists.
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
OSPF DR/BDR election is influenced by interface priority. A priority of 0 makes a router ineligible to become DR or BDR. The other options either do not exist, change the network type unnecessarily, or increase the likelihood of becoming DR. Therefore, setting priority to 0 on each interface is the correct approach.
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 255
Why it's wrong here
Setting priority to 255 makes the router more likely to become DR, not less. The highest priority wins the DR election; 255 is the maximum value and would almost certainly cause the router to become DR if it has the highest priority. This is the opposite of the desired outcome.
- ✗
ip ospf network point-to-point
Why it's wrong here
Changing the OSPF network type to point-to-point eliminates DR/BDR election on that interface, but it also changes the adjacency behavior and may not be desired if the segment is a broadcast network with multiple routers. The requirement is only to prevent this router from becoming DR, not to change the network type.
- ✗
ip ospf dr-disable
Why it's wrong here
There is no OSPF command 'ip ospf dr-disable' on Cisco IOS. While some routing protocols have commands to disable specific roles, OSPF uses priority to influence DR election. This command does not exist, so it would be rejected by the router and would not achieve the goal.
- ✓
ip ospf priority 0
Why this is correct
Setting OSPF priority to 0 on an interface makes the router ineligible to become DR or BDR on that interface. This is the correct method to prevent a router from being elected as DR. The priority value is carried in Hello packets and used in the DR election process; a priority of 0 means the router will not participate in the election.
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.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,401 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or 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 300-410 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 300-410 exam.