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300-410 Router R1 and R2 are running OSPF in area 0 Practice Question
Router R1 and R2 are running OSPF in area 0. R1 has a loopback interface with IP 192.168.1.1/32 advertised into OSPF. R2 learns this route as an intra-area route (AD 110). R2 also runs RIP and learns the same prefix from R3 with AD 120. R2's 'show ip route 192.168.1.1' shows the RIP route. What is the root cause?
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
✓
R2's OSPF process has 'distance 130' configured, making OSPF routes have AD 130, which is higher than RIP's AD 120.
RIP has AD 120, OSPF has AD 110, so OSPF should be preferred. If the OSPF route is not installed, it could be due to a higher metric or a filter. The correct answer is that the OSPF route is an external route (type-5) because it was redistributed from another protocol, not an intra-area route. The scenario says intra-area, but if the loopback is not directly connected to OSPF (e.g., it is in a different VRF), it might be redistributed as external. The question states it is advertised into OSPF, but the AD for external is 110, same as intra-area. The trick is that the OSPF route might have a higher metric than the RIP route, but AD is checked first. The most likely cause is that the OSPF route is not in the routing table due to a distribute-list or because the OSPF process has 'distance 130' configured for all routes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
R2's OSPF process has 'distance 130' configured, making OSPF routes have AD 130, which is higher than RIP's AD 120.
Why this is correct
If OSPF distance is set to 130, RIP (120) becomes preferred.
- ✗
The RIP route has a better metric than the OSPF route.
Why it's wrong here
AD is compared before metric.
- ✗
R2 has a static route with AD 1 that overrides both.
Why it's wrong here
No static route.
- ✗
The OSPF route is an external route with AD 170 due to redistribution.
Why it's wrong here
OSPF external routes have AD 110, not 170.
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
Learn chapter
OSPF Neighbor Adjacency and Basics
Key term
ACL for Routing Protocols
An ACL for Routing Protocols is a set of rules used to filter routing updates between routers, controlling which network routes are advertised or accepted to improve security and stability.
Key term
MPLS Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.