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300-410 Practice Question: Is troubleshooting a connectivity issue between…
A network engineer is troubleshooting a connectivity issue between two sites. R1 learns the prefix 10.0.0.0/8 via RIP (AD 120) from R2, and also via a directly connected interface on R3. The engineer notices that R1 uses the RIP route instead of the connected route. What is the most likely 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
✓
The RIP route has an AD of 120, but the connected route is for a different subnet mask.
Connected routes have an AD of 0, which is always preferred over any dynamic routing protocol. If the connected route is not used, it likely does not exist for that exact prefix, or the interface is down. However, if the prefix is learned via RIP with AD 120, the connected route should take precedence. The only way RIP is preferred is if the connected route is not present for that prefix.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The connected interface on R3 has a higher metric than the RIP route.
Why it's wrong here
Connected routes have AD 0, so they are always preferred regardless of metric.
- ✓
The RIP route has an AD of 120, but the connected route is for a different subnet mask.
Why this is correct
If the connected route is for 10.0.0.0/16 and the RIP route is for 10.0.0.0/8, they are different prefixes; the router will use the most specific match, but if the connected route is not for the exact prefix, RIP may be the only route.
- ✗
The distance rip 0 command was applied under RIP, making RIP routes have AD 0.
Why it's wrong here
If RIP AD were set to 0, it would tie with the connected route, but the router would still prefer the connected route due to route type preference (connected is directly attached).
- ✗
The connected interface is administratively down.
Why it's wrong here
If the interface is down, the connected route is removed, so RIP would be the only route, but the question states the connected route is learned from R3, implying it exists.
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.
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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.