The correct answer is that the router is acting as an NHRP server and successfully resolves the NBMA address for the target. This is because the debug output shows the router receiving a Resolution Request and immediately sending a Resolution Reply, which is the exact behavior of a hub in a DMVPN topology that has a cached mapping for the target 192.168.1.1. The key technical concept here is that the NHRP server resolves the logical tunnel IP to the physical NBMA address (10.1.1.2) and responds directly, enabling spoke-to-spoke communication. On the Cisco CCNP ENARSI 300-410 exam, this debug output tests your ability to distinguish between hub and spoke NHRP roles; a common trap is confusing a Resolution Reply with a Registration Reply. A strong memory tip is “Request comes in, Reply goes out—that’s the hub’s job,” so if you see both messages in sequence, the router is acting as the NHRP server.
300-410 Device Access Control Practice Question
This 300-410 practice question tests your understanding of device access control. 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 runs the following command to troubleshoot a Device Access Control issue:
R1# debug nhrp
NHRP: Receive Resolution Request via Tunnel0 10.1.1.2, target 192.168.1.1
NHRP: Send Resolution Reply via Tunnel0 to 10.1.1.2, target 192.168.1.1
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is acting as a NHRP server and successfully resolves the NBMA address for the target.
The debug output shows the router receiving a Resolution Request and immediately sending a Resolution Reply, which is the behavior of a Next Hop Resolution Protocol (NHRP) server (or hub) that has a mapping for the target 192.168.1.1. The router successfully resolves the Non-Broadcast Multiple Access (NBMA) address (10.1.1.2) for the target, indicating it is acting as a server in a DMVPN or similar overlay network.
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.
✓
The router is acting as a NHRP server and successfully resolves the NBMA address for the target.
Why this is correct
The router receives a request and sends a reply, indicating it has the mapping and is providing resolution.
Related concept
Read the scenario before looking for a memorised answer.
✗
The router is a NHRP client and is requesting resolution for target 192.168.1.1.
Why it's wrong here
The router receives a request, not sends one; it is acting as a server.
✗
The router is unable to resolve the target address because it does not have a mapping.
Why it's wrong here
The router sends a reply, which means it has the mapping and can resolve the address.
✗
The NHRP process is failing due to a misconfigured authentication key.
Why it's wrong here
There is no indication of authentication failure; the exchange is successful.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between NHRP client (spoke) and server (hub) roles by showing debug output; the trap here is that candidates may confuse sending a Resolution Reply with sending a Resolution Request, incorrectly assuming the router is a client.
Detailed technical explanation
How to think about this question
NHRP operates in a hub-and-spoke DMVPN topology where the hub (server) maintains a mapping database of tunnel (NBMA) addresses to target (protocol) addresses. When a spoke sends a Resolution Request, the hub replies with the NBMA address of the destination spoke, enabling direct spoke-to-spoke tunnels. The debug output confirms the hub has the mapping cached, likely learned via NHRP Registration from the target spoke.
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.
TExam Day Tips
→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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Device Access Control — This question tests Device Access Control — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The router is acting as a NHRP server and successfully resolves the NBMA address for the target. — The debug output shows the router receiving a Resolution Request and immediately sending a Resolution Reply, which is the behavior of a Next Hop Resolution Protocol (NHRP) server (or hub) that has a mapping for the target 192.168.1.1. The router successfully resolves the Non-Broadcast Multiple Access (NBMA) address (10.1.1.2) for the target, indicating it is acting as a server in a DMVPN or similar overlay network.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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