350-501 Architecture Practice Question
A network engineer is configuring MPLS LDP on a new router. After enabling LDP globally and on the interface, the LDP session does not establish. The IGP (OSPF) is fully operational. What should the engineer verify first?
⚠ Common exam trap
Cisco often tests the distinction between enabling LDP globally versus enabling it on the interface, trapping candidates who assume global configuration alone is sufficient for LDP to operate on all 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
✓
The interface has 'mpls ip' enabled.
The most common reason LDP fails to establish after global and interface configuration is that the interface is not enabled for MPLS forwarding. The command 'mpls ip' on the interface is required to activate LDP hello messages and label binding on that link. Without it, LDP remains disabled on the interface even if LDP is enabled globally and OSPF is working.
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 LDP password matches.
Why it's wrong here
While password mismatch can prevent session establishment, it is not the first thing to check if no authentication is configured.
- ✗
The router-id is a loopback.
Why it's wrong here
LDP can use any IP address as router-id, and a loopback is not mandatory.
- ✗
The IGP metric is set.
Why it's wrong here
IGP metric does not affect LDP session establishment; LDP uses IGP to resolve transport addresses, but metric is irrelevant.
- ✓
The interface has 'mpls ip' enabled.
Why this is correct
This is the most basic verification; if MPLS is not enabled on the interface, LDP will not form.
Visual reference
Go deeper
Related to this question
About these practice questions
Courseiva writes every 350-501 question from scratch — 971 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 350-501 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 350-501 exam.