CCNA IP Routing Practice Question
Which TWO statements correctly describe the behavior of the passive-interface command in single-area OSPFv2?
⚠ Common exam trap
A common mistake is confusing passive-interface in OSPF with RIP or EIGRP; in OSPF, it suppresses all control packets on the interface, but the network is still advertised in LSAs via other interfaces.
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
✓
It prevents the router from sending Hello packets on the specified interface.
The passive-interface command in OSPFv2 suppresses all OSPF protocol packets (Hello, DD, LSR, LSU, LSAck) on the specified interface, preventing neighbor adjacency formation. However, the network prefix of that interface is still included in the router LSA and advertised through active interfaces to the OSPF domain. Option A is correct because Hello packets are suppressed. Option C is correct because the prefix is still advertised in LSAs. Option B is incorrect after rewording: it states that the network is not advertised, which is false. Option D is incorrect because passive-interface does not affect data traffic forwarding. Option E is incorrect because the network remains in the OSPF routing table.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
It prevents the router from sending Hello packets on the specified interface.
Why this is correct
This is correct: the passive-interface command in OSPF suppresses the transmission of Hello packets on the specified interface. Without Hello packets, the router cannot discover neighbors or form adjacencies on that link, so no OSPF neighbor relationship will ever establish. This is commonly used on broadcast or point-to-multipoint segments where OSPF peering is not needed but the subnet must still be advertised.
- ✗
It prevents the router from advertising the network in OSPF LSAs.
Why it's wrong here
This is incorrect because OSPF still advertises the network associated with a passive interface. The passive configuration does not remove the network from the OSPF link-state database; instead, the subnet is included as a stub network in the Type 1 Router LSA, which is advertised to all OSPF neighbors. Therefore, the network remains reachable via OSPF, and this option's statement directly contradicts the actual behavior of passive-interface.
- ✓
The network associated with the passive interface is still advertised in OSPF LSAs.
Why this is correct
This is correct: even when an OSPF interface is configured as passive, its attached network is still injected into the OSPF link-state database. Specifically, the subnet appears as a stub network entry in the router's Type 1 LSA, which is flooded to neighbors. Consequently, other OSPF routers learn the route and will route traffic toward it, even though no adjacency forms on the passive interface itself.
- ✗
It disables the interface for any OSPF traffic, including data traffic.
Why it's wrong here
This is wrong because a passive OSPF interface does not affect the data plane. The interface continues to forward ordinary IP data traffic exactly as before; passive-interface only stops the exchange of OSPF control packets like Hellos and, implicitly, the processing of incoming OSPF packets. User traffic is forwarded based on the routing table, which still contains the route for this network, so the interface remains fully operational for data forwarding.
- ✗
It removes the network from the OSPF routing table.
Why it's wrong here
This is incorrect because the OSPF route for the network remains in the IP routing table. A passive interface still participates in OSPF's link-state database by having its subnet advertised as a stub network in the Type 1 Router LSA, so the router continues to install and use the route for forwarding traffic. Passive-interface only suppresses OSPF protocol exchanges on that link, not routing information.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓It prevents the router from sending Hello packets on the specified interface.Correct answer▾
Why this is correct
This is correct: the passive-interface command in OSPF suppresses the transmission of Hello packets on the specified interface. Without Hello packets, the router cannot discover neighbors or form adjacencies on that link, so no OSPF neighbor relationship will ever establish. This is commonly used on broadcast or point-to-multipoint segments where OSPF peering is not needed but the subnet must still be advertised.
✗It prevents the router from advertising the network in OSPF LSAs.Wrong answer — click to see why▾
Why this is wrong here
This is false because the network under a passive interface is still included in the router LSA and advertised through active interfaces.
Why candidates choose this
Students often confuse OSPF with distance vector protocols like RIP, where the passive-interface command stops sending routing updates. In OSPF, the term 'routing updates' is misleading because OSPF uses LSAs, not periodic updates.
✗It disables the interface for any OSPF traffic, including data traffic.Wrong answer — click to see why▾
Why this is wrong here
The passive-interface command only affects OSPF control plane traffic (Hello packets) on the interface. Data traffic is still forwarded normally through the interface, and the interface remains fully operational for all other protocols and forwarding.
Why candidates choose this
The word 'passive' might imply that the interface is disabled or inactive for all traffic. However, in OSPF context, it only means the interface does not actively send Hello packets to discover neighbors.
✗It removes the network from the OSPF routing table.Wrong answer — click to see why▾
Why this is wrong here
The passive-interface command does not remove the network from the OSPF routing table. The network is still advertised via LSAs and remains in the routing table as an OSPF route. The command only prevents the interface from forming OSPF adjacencies.
Why candidates choose this
Some might think that if an interface is passive, its network should not be advertised. However, OSPF still includes the network in LSAs to ensure reachability, even if no neighbors are on that interface.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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
OSPFv3 Single-Area Configuration for IPv6
Key term
LSA
A Link State Advertisement is a data packet used by OSPF routers to share information about their directly connected links and the state of those links with all other routers in the OSPF network.
Key term
LSA
A Link State Advertisement (LSA) is a data packet used by the OSPF routing protocol to share information about network links and topology with neighboring routers.
About these practice questions
Courseiva writes every 200-301 question from scratch — 1,389 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.