The correct answer is that NHRP Registration Request packets are used to register the spoke’s tunnel IP and NBMA address with the hub. This is because in a DMVPN network, the hub acts as the Next Hop Server (NHS), and each spoke must dynamically inform the hub of its logical tunnel interface IP and its physical Non-Broadcast Multiple Access (NBMA) address, typically a public or private WAN IP. Without this registration, the hub cannot build its NHRP mapping table, which is essential for forwarding traffic between spokes or from the hub to the spoke. On the Cisco CCNP ENARSI 300-410 exam, this concept tests your understanding of the DMVPN control plane, often appearing in questions that contrast registration with resolution requests or that present a scenario where a spoke cannot establish a tunnel. A common trap is confusing the Registration Request with the Resolution Request—remember that registration is spoke-to-hub for initial mapping, while resolution is spoke-to-hub to learn another spoke’s address. A useful memory tip is “Register your address, resolve to find others.”
300-410 DMVPN Practice Question
This 300-410 practice question tests your understanding of dmvpn. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which statement about the Next Hop Resolution Protocol (NHRP) in DMVPN is correct regarding the purpose of NHRP Registration Request packets?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
They are used to register the spoke's tunnel IP and NBMA address with the hub.
NHRP Registration Request packets are sent from spoke routers to the hub to register their tunnel IP address (NHS) and corresponding NBMA address. This allows the hub to build a mapping database for forwarding.
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.
✗
They are used to resolve the NBMA address of a destination tunnel IP address.
Why it's wrong here
Incorrect. Resolution of NBMA addresses is done via NHRP Resolution Request/Reply, not Registration.
✓
They are used to register the spoke's tunnel IP and NBMA address with the hub.
Why this is correct
Correct. Registration Request packets register the spoke's mapping with the hub.
Related concept
Static NAT maps one inside address to one outside address.
✗
They are used to purge outdated NHRP cache entries on the hub.
Why it's wrong here
Incorrect. Purge is done via NHRP Purge Request packets.
✗
They are used to establish an IPsec security association between spokes.
Why it's wrong here
Incorrect. IPsec SA establishment is separate and uses IKE, not NHRP.
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.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
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.
DMVPN — This question tests DMVPN — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: They are used to register the spoke's tunnel IP and NBMA address with the hub. — NHRP Registration Request packets are sent from spoke routers to the hub to register their tunnel IP address (NHS) and corresponding NBMA address. This allows the hub to build a mapping database for forwarding.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. What is the default authentication type for NHRP in a DMVPN configuration?
easy
A.Plaintext password
B.MD5 hash
✓ C.No authentication
D.IPsec
Why C: By default, NHRP does not use any authentication. Authentication can be configured using the 'ip nhrp authentication' command, but it is disabled by default.
Variation 2. What is the default NHRP holdtime value on a Cisco router?
easy
✓ A.3600 seconds
B.1800 seconds
C.7200 seconds
D.600 seconds
Why A: The default NHRP holdtime is 3600 seconds (1 hour). This value can be modified with the 'ip nhrp holdtime' command.
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.