The answer is to configure label filtering, enable LDP on all core interfaces, and enable LDP authentication. These three practices secure the MPLS core by limiting label distribution to only necessary peers, ensuring full reachability across the backbone, and protecting against spoofed label-switched path attacks. On the Cisco SPCOR 350-501 exam, this question tests your ability to distinguish between default behaviors and deliberate security hardening—a common trap is confusing the optional explicit-null label with a best practice, or assuming holdtime adjustments are recommended. Remember the mnemonic "FLA" for Filtering, LDP on all core interfaces, and Authentication; this directly maps to the exam’s emphasis on operational security over tuning non-critical timers.
350-501 Architecture Practice Question
This 350-501 practice question tests your understanding of architecture. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer is designing a new MPLS core. Which three of the following are recommended best practices for MPLS LDP configuration? (Choose three.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Enabling LDP on all core interfaces (A), configuring label filtering (C) for security, and enabling LDP authentication (D) are best practices. Explicit null (B) is not a default best practice; holdtime (E) is default 180 seconds and not a specific best practice.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable LDP on all core interfaces
Why this is correct
LDP should be enabled on all core interfaces to ensure label distribution.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Configure label filtering to limit label distribution
Why this is correct
Label filtering enhances security and control by limiting which labels are advertised.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 350-501 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Architecture — This question tests Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable LDP authentication using MD5 — Enabling LDP on all core interfaces (A), configuring label filtering (C) for security, and enabling LDP authentication (D) are best practices. Explicit null (B) is not a default best practice; holdtime (E) is default 180 seconds and not a specific best practice.
What should I do if I get this 350-501 question wrong?
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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