- A
The router in the explicit path does not have MPLS TE enabled.
Correct because for a router to appear in the TED, MPLS TE must be enabled globally and on its interfaces; otherwise, the headend cannot include it in the path.
- B
The explicit path is configured with a loose next-hop.
Why wrong: Incorrect because loose next-hops are allowed in explicit paths; the issue is that the router is not in the TED at all.
- C
The tunnel destination is not reachable via the IGP.
Why wrong: Incorrect because TE tunnels do not require IGP reachability to the destination; they use the TED for path computation.
- D
The mpls traffic-eng tunnels command is missing on the headend.
Why wrong: Incorrect because the tunnel is configured and the headend is attempting path computation; the command is present.
300-410 MPLS Operations Practice Question
This 300-410 practice question tests your understanding of mpls operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 troubleshooting MPLS TE where a tunnel is configured with explicit path but the tunnel remains down. The show mpls traffic-eng tunnels command shows 'Path computation failed' and the show mpls traffic-eng topology command shows that the explicit path includes a router that is not in the TED. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 router in the explicit path does not have MPLS TE enabled.
The explicit path includes a router that is not in the TED, meaning the headend cannot find that router in the traffic engineering database. This is because MPLS TE is not enabled on that router or its interfaces, so its link attributes are not advertised.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 router in the explicit path does not have MPLS TE enabled.
Why this is correct
Correct because for a router to appear in the TED, MPLS TE must be enabled globally and on its interfaces; otherwise, the headend cannot include it in the path.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
The explicit path is configured with a loose next-hop.
Why it's wrong here
Incorrect because loose next-hops are allowed in explicit paths; the issue is that the router is not in the TED at all.
- ✗
The tunnel destination is not reachable via the IGP.
Why it's wrong here
Incorrect because TE tunnels do not require IGP reachability to the destination; they use the TED for path computation.
- ✗
The mpls traffic-eng tunnels command is missing on the headend.
Why it's wrong here
Incorrect because the tunnel is configured and the headend is attempting path computation; the command is present.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Command / output trap
Incorrect because the tunnel is configured and the headend is attempting path computation; the command is present.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 300-410 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 300-410 question test?
MPLS Operations — This question tests MPLS Operations — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The router in the explicit path does not have MPLS TE enabled. — The explicit path includes a router that is not in the TED, meaning the headend cannot find that router in the traffic engineering database. This is because MPLS TE is not enabled on that router or its interfaces, so its link attributes are not advertised.
What should I do if I get this 300-410 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 300-410 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
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Last reviewed: Jun 18, 2026
This 300-410 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 300-410 exam.
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