hardMultiple Choice
300-410 EIGRP Successor Practice Question
EIGRP network with routers R1, R2, R3. R1 has:
router eigrp 100 network 10.0.0.0
R2 has:
router eigrp 100 network 10.0.0.0
R3 has:
router eigrp 100 network 10.0.0.0
R1 shows:
R1# show ip eigrp topology 10.1.1.0/24
EIGRP-IPv4 Topology Entry for 10.1.1.0/24 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 128256 Routing Descriptor Blocks:
10.2.1.2 (Serial0/0/0), from 10.2.1.2, Send flag is 0x0
Composite metric is (128256/156160), Route is Internal
10.3.1.3 (Serial0/0/1), from 10.3.1.3, Send flag is 0x0
Composite metric is (156160/128256), Route is Internal
R1# show ip route 10.1.1.0
Routing entry for 10.1.1.0/24 Known via "eigrp 100", distance 90, metric 128256 Last update from 10.2.1.2 on Serial0/0/0 An engineer expected R1 to use the path via 10.3.1.3 because it appears in the topology table, but R1 is using the path via 10.2.1.2. What is the reason?
⚠ Common exam trap
Candidates may misread the show ip eigrp topology output and assume the path with higher metric is used, but the routing table shows the actual installed route. Always verify with show ip route.
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 path with higher FD is not feasible; EIGRP always selects the lowest FD.
The show ip route output confirms that R1 installed the route via 10.2.1.2 with metric 128256, the lowest feasible distance. The path via 10.3.1.3 has a higher local metric (156160) and is not the successor. EIGRP always selects the route with the lowest FD, so the higher-FD path is not used. Option A is correct.
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 path with higher FD is not feasible; EIGRP always selects the lowest FD.
Why this is correct
Correct. EIGRP always selects the path with the lowest feasible distance as the successor. The higher FD path is not feasible as a successor because it has a higher metric. The show ip route output confirms the lower FD path is installed.
- ✗
An offset-list is applied to the lower FD path, increasing its metric.
Why it's wrong here
Incorrect. There is no evidence of an offset-list. If one were applied to increase the lower FD path's metric, the higher FD path might become the successor, but the routing table shows the lower metric path is still used.
- ✗
The route is in active state, causing EIGRP to use a backup path.
Why it's wrong here
Incorrect. The topology entry shows the state is Passive, not Active. An active state would indicate query propagation, not the use of a backup path.
- ✗
R1 has a distribute-list blocking the lower FD path.
Why it's wrong here
Incorrect. While a distribute-list could filter routes, there is no output showing filtering. The shown routes are both in the topology table, and the lower FD route is installed in the routing table.
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.