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CCNP Practice Question: Which three statements about LDP (Label…
Which three statements about LDP (Label Distribution Protocol) are true? (Choose three.)
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
✓
LDP uses UDP to send Hello messages for neighbor discovery.
LDP uses Hello messages (UDP on port 646) for neighbor discovery and TCP (port 646) for session establishment and label exchange. LDP assigns labels to all prefixes in the routing table by default. LDP does not support traffic engineering; RSVP-TE is used for that. LDP does not use OSPF for label distribution; it has its own discovery and session mechanisms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
LDP uses UDP to send Hello messages for neighbor discovery.
Why this is correct
Correct because LDP Hellos are sent as UDP packets to the multicast address 224.0.0.2 on port 646.
- ✓
LDP establishes TCP sessions between LSRs to exchange label bindings.
Why this is correct
Correct because after discovery, LDP uses TCP (port 646) for reliable label exchange.
- ✓
LDP assigns labels to all prefixes in the routing table by default.
Why this is correct
Correct because LDP by default allocates labels for every route in the IP routing table.
- ✗
LDP supports traffic engineering by reserving bandwidth along LSPs.
Why it's wrong here
Incorrect because LDP does not support traffic engineering; RSVP-TE is used for that.
- ✗
LDP uses OSPF to distribute label bindings across the network.
Why it's wrong here
Incorrect because LDP uses its own protocol (UDP/TCP) for label distribution, not OSPF.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.