easyMultiple Select
350-401 Practice Question: Which two statements about OSPF neighbor states…
Which two statements about OSPF neighbor states are true? (Choose two.)
⚠ Common exam trap
It's easy for candidates to confuse the ExStart/Exchange/Loading states — candidates often mix up which packets (DBD, LSR, LSU) are exchanged in which state, and mistakenly think Down is a terminal state rather than the initial one.
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 2-Way state indicates that both routers have seen their own router ID in the neighbor's hello packet.
Option A is correct because the 2-Way state is reached when a router receives a Hello packet from a neighbor that contains its own Router ID in the neighbor list field, confirming bidirectional communication. Option B is correct because Full state means the two routers have successfully completed database synchronization, so their link-state databases (LSDBs) are identical and they are fully adjacent. Option C is incorrect because Database Description (DBD) packets with LSA headers are exchanged in the Exchange state, not the ExStart state; ExStart only negotiates the master/slave relationship and initial DBD sequence numbers. Option D is incorrect because Link State Requests and Link State Updates are exchanged in the Loading state, not the Exchange state. Option E is incorrect because Down is the initial state, not the final state, when no Hello packets have been received from the neighbor.
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 2-Way state indicates that both routers have seen their own router ID in the neighbor's hello packet.
Why this is correct
2-Way is declared once each router sees its own Router ID listed in the neighbour's Hello packet, proving two-way reachability. This bidirectional confirmation is the defining mechanism of the state, so the statement accurately describes when it is reached.
- ✓
The Full state indicates that the routers have synchronized their LSDBs and are fully adjacent.
Why this is correct
Full follows successful Database Description and Link State Request exchange, after which the routers' link-state databases are identical and they are fully adjacent. The statement correctly ties the state to completed LSDB synchronisation between neighbours.
- ✗
In the ExStart state, routers exchange Database Description packets containing LSA headers.
Why it's wrong here
ExStart negotiates master/slave roles and initial sequence numbers via empty Database Description packets; LSA headers are carried in Exchange, not ExStart. It is tempting because DD packets do appear here, but the payload differs by state.
- ✗
In the Exchange state, routers send Link State Requests and receive Link State Updates.
Why it's wrong here
Incorrect because LSRs and LSUs are exchanged in the Loading state, not the Exchange state.
- ✗
The Down state is the final state when a neighbor is unreachable.
Why it's wrong here
Down is not a terminal state; it is the initial state before Hello packets are received, and a neighbour can return to it after an inactivity timer expires. It is tempting because unreachable neighbours sit there, but adjacency can restart.
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.
About these practice questions
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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which two statements about OSPF neighbor states are true? (Choose two.)
medium- ✓ A.The 2-Way state indicates that the router has received a Hello packet from the neighbor with its own Router ID in the neighbor list.
- B.In the ExStart state, routers exchange Database Description (DBD) packets to describe their LSDB contents.
- ✓ C.The Full state means the routers have synchronized their link-state databases and are fully adjacent.
- D.The Loading state occurs before the Exchange state in the neighbor state machine.
- E.The Down state means the router has received a Hello packet from the neighbor but has not yet established two-way communication.
Why A: Option A is correct because in the OSPF neighbor state machine, the 2-Way state is reached when a router sees its own Router ID listed in the Neighbor field of a received Hello packet, confirming bidirectional communication. Option C is correct because Full state is the final adjacency state, meaning the two routers have successfully exchanged all LSAs and their link-state databases are synchronized. Option B is incorrect because DBD packet exchange occurs in the Exchange state, not ExStart; ExStart is where the master/slave relationship and initial DBD sequence numbers are negotiated. Option D is incorrect because the correct order is ExStart, then Exchange, then Loading, so Loading does not occur before Exchange. Option E is incorrect because Down means no Hello packets have been received from the neighbor (or the neighbor is dead), while receiving a Hello without two-way communication established corresponds to the Init state.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.