mediumMultiple Choice
300-410 Practice Question: Consider the following EIGRP configuration on…
Consider the following EIGRP configuration on Router R1:
router eigrp 100 network 10.0.0.0 passive-interface default no passive-interface GigabitEthernet0/0
What is the effect of this configuration?
⚠ Common exam trap
Cisco often tests the interaction between 'passive-interface default' and 'no passive-interface', where candidates mistakenly think the default command blocks all adjacencies permanently or confuse which interfaces are enabled versus disabled.
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
✓
EIGRP will form neighbor adjacencies only on GigabitEthernet0/0.
The 'passive-interface default' command sets all interfaces to passive by default, preventing EIGRP from sending or receiving hello packets on them. The 'no passive-interface GigabitEthernet0/0' command then overrides this default for that specific interface, allowing EIGRP to send and receive hellos and thus form neighbor adjacencies only on GigabitEthernet0/0.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
EIGRP will form neighbor adjacencies on all interfaces.
Why it's wrong here
The passive-interface default command disables Hellos on all interfaces, and no passive-interface GigabitEthernet0/0 re-enables only that interface, so adjacencies form solely on GigabitEthernet0/0, not on all interfaces. It is tempting because no passive-interface does re-enable an interface, but only the named one.
- ✓
EIGRP will form neighbor adjacencies only on GigabitEthernet0/0.
Why this is correct
Passive-interface default suppresses EIGRP hello packets on every interface, preventing adjacency formation there. The no passive-interface GigabitEthernet0/0 exception re-enables hellos solely on that interface, so neighbours can only be discovered and adjacencies formed on GigabitEthernet0/0, satisfying the stem's configuration exactly.
- ✗
EIGRP will not form any neighbor adjacencies.
Why it's wrong here
The no passive-interface GigabitEthernet0/0 line re-enables Hellos on that interface, so EIGRP does form an adjacency there despite the passive default. It is tempting because passive-interface default alone blocks all adjacencies, which is the correct outcome only when no interface is explicitly re-enabled.
- ✗
EIGRP will form neighbor adjacencies on all interfaces except GigabitEthernet0/0.
Why it's wrong here
Passive-interface default suppresses EIGRP hellos on every interface, and the no passive-interface exception re-enables GigabitEthernet0/0, so adjacencies form only there. The option inverts this. Passive interfaces suit stub or user-facing segments where adjacency formation is unwanted.
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.