350-501 Security and Services Practice Question
An MPLS L3VPN service provider wants to prevent label spoofing attacks where a customer could inject MPLS labels to bypass ACLs. Which configuration practice should be implemented on PE-CE links?
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
✓
Disable MPLS on PE-CE links
To prevent label spoofing, MPLS should be disabled on PE-CE links so that customers cannot send labeled packets. Additionally, disabling TTL propagation prevents label stack visibility.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Disable MPLS on PE-CE links
Why this is correct
Disabling MPLS on PE-CE links prevents customers from sending labeled packets.
- ✗
Enable MPLS TTL propagation to detect spoofing
Why it's wrong here
TTL propagation does not prevent spoofing; it exposes the label stack.
- ✗
Enable MPLS on PE-CE links with TTL propagation disabled
Why it's wrong here
Enabling MPLS on PE-CE links exposes the label stack and allows spoofing.
- ✗
Use explicit null labels on PE-CE links
Why it's wrong here
Explicit null is for penultimate hop popping, not for security.
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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.