350-501 Architecture Practice Question
A network engineer is designing a new MPLS core. Which three of the following are recommended best practices for MPLS LDP configuration? (Choose three.)
⚠ Common exam trap
Cisco often tests the distinction between explicit null (label 0) and implicit null (label 3) for BGP prefixes, leading candidates to mistakenly choose explicit null as a best practice when it is actually used only for specific purposes like QoS marking.
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
✓
Enable LDP authentication using MD5
C is correct because enabling LDP authentication using MD5 protects the LDP session from spoofing and tampering by verifying the integrity of TCP segments exchanged between LDP peers. This is a recommended security best practice in MPLS networks to prevent unauthorized label distribution and route hijacking.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use explicit null label for BGP prefixes
Why it's wrong here
Explicit null is optional and not a general best practice; often implicit null is used.
- ✗
Set the LDP session holdtime to 180 seconds
Why it's wrong here
180 seconds is the default holdtime; adjusting it is not a general best practice.
- ✓
Enable LDP authentication using MD5
Why this is correct
LDP authentication protects against spoofing and is a security best practice.
- ✓
Enable LDP on all core interfaces
Why this is correct
LDP should be enabled on all core interfaces to ensure label distribution.
- ✓
Configure label filtering to limit label distribution
Why this is correct
Label filtering enhances security and control by limiting which labels are advertised.
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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.