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300-410 Practice Question: EIGRP stuck-in-active (SIA) is occurring due to…
EIGRP stuck-in-active (SIA) is occurring due to route summarization. Router R1 is the hub in a hub-and-spoke topology with R2 and R3 as spokes. R1's configuration:
interface GigabitEthernet0/0 ip address 10.0.0.1 255.255.255.0 ip summary-address eigrp 100 10.0.0.0 255.255.252.0
!
router eigrp 100 network 10.0.0.0
! R2 and R3 are connected via Frame Relay. R2 shows:
R2# show ip eigrp topology 10.0.1.0/24
P 10.0.1.0/24, 1 successors, FD is 30720 via 10.0.0.1 (30720/28160), GigabitEthernet0/0 R3 has a similar entry. However, when R1's summary is active, R2 and R3 go into active state for the summary. 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
✓
The summary route causes EIGRP queries to loop between spokes when one loses connectivity, leading to SIA.
The summary route 10.0.0.0/22 is advertised by R1 to both spokes. If one spoke loses connectivity to R1, it queries the other spoke for the summary. The spoke may not have a route to the summary, causing it to query R1 again, leading to a query loop and SIA. The summary should be configured with a leak-map to allow specific routes, or the query scope should be limited.
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 summary route causes EIGRP queries to loop between spokes when one loses connectivity, leading to SIA.
Why this is correct
Spokes query each other for the summary, and if neither has a route, they query the hub again, causing a loop.
- ✗
The Frame Relay network is not supporting multicast, so EIGRP hello packets are lost.
Why it's wrong here
Hellos are not the issue; SIA is due to query propagation.
- ✗
The summary route metric is too high, causing EIGRP to not install it.
Why it's wrong here
Metric does not cause SIA.
- ✗
EIGRP is not enabled on the spoke interfaces.
Why it's wrong here
Spokes have EIGRP routes.
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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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.