- A
The spokes are missing the 'ip nhrp nhs' command to point to the hub, preventing registration and resolution of spoke-to-spoke addresses.
Without NHS configuration, spokes do not register with the hub, so NHRP cannot provide the mapping for spoke-to-spoke tunnels.
- B
The tunnel mode is mGRE, but the spokes are configured with point-to-point GRE tunnels.
Why wrong: Spokes typically use mGRE as well; if they used p2p GRE, they would only connect to the hub, but the scenario does not indicate this.
- C
The NHRP network-id is different on R2 and R3, preventing communication.
Why wrong: The network-id must match, but the scenario shows it is 1 on the hub; if spokes had different IDs, they would not register.
- D
The tunnel source interface is not reachable between spokes.
Why wrong: Spoke-to-spoke reachability is established via NHRP; if NHRP is not working, the tunnel source may be reachable but the tunnel itself fails.
Quick Answer
The answer is that the spokes are missing the 'ip nhrp nhs' command pointing to the hub, which prevents NHRP registration and breaks spoke-to-spoke tunnel formation. Without this command, R2 and R3 never register their real (physical) addresses with the hub, so the hub cannot relay those addresses to other spokes via NHRP resolution replies. When a spoke tries to build a direct tunnel to another spoke, it has no NHRP mapping to resolve—hence the 'show dmvpn' shows no dynamic sessions and 'show ip nhrp' shows no entries for the peer. On the Cisco CCNP ENARSI 300-410 exam, this is a classic trap: candidates often focus on the hub's 'ip nhrp map multicast dynamic' and assume spokes will automatically register, but the spokes must explicitly declare the hub as their NHS. A common memory tip is "Spokes need NHS to speak"—without the NHS command, the spoke never introduces itself, and the DMVPN cloud stays silent.
300-410 Device Management Practice Question
This 300-410 practice question tests your understanding of device management. 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 DMVPN network with hub R1 and spokes R2 and R3 is configured with mGRE and NHRP. Spoke-to-spoke tunnels fail to form. R1 configuration: interface Tunnel0, ip address 10.0.0.1 255.255.255.0, tunnel source GigabitEthernet0/0, tunnel mode gre multipoint, ip nhrp network-id 1, ip nhrp map multicast dynamic. R2 shows: 'show dmvpn' shows no dynamic sessions. R3 shows: 'show ip nhrp' shows no entries for R2. What is the root cause?
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 spokes are missing the 'ip nhrp nhs' command to point to the hub, preventing registration and resolution of spoke-to-spoke addresses.
For spoke-to-spoke tunnels to form, NHRP must be configured to allow spoke registration and resolution. The hub configuration includes 'ip nhrp map multicast dynamic', which allows spokes to register, but spokes must also have 'ip nhrp nhs' pointing to the hub. If R2 and R3 do not have NHRP server configuration, they will not register, and thus cannot learn each other's addresses. The root cause is missing NHRP NHS configuration on the spokes.
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 spokes are missing the 'ip nhrp nhs' command to point to the hub, preventing registration and resolution of spoke-to-spoke addresses.
Why this is correct
Without NHS configuration, spokes do not register with the hub, so NHRP cannot provide the mapping for spoke-to-spoke tunnels.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The tunnel mode is mGRE, but the spokes are configured with point-to-point GRE tunnels.
Why it's wrong here
Spokes typically use mGRE as well; if they used p2p GRE, they would only connect to the hub, but the scenario does not indicate this.
- ✗
The NHRP network-id is different on R2 and R3, preventing communication.
Why it's wrong here
The network-id must match, but the scenario shows it is 1 on the hub; if spokes had different IDs, they would not register.
- ✗
The tunnel source interface is not reachable between spokes.
Why it's wrong here
Spoke-to-spoke reachability is established via NHRP; if NHRP is not working, the tunnel source may be reachable but the tunnel itself fails.
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.
Trap categories for this question
Command / output trap
The network-id must match, but the scenario shows it is 1 on the hub; if spokes had different IDs, they would not register.
Scenario analysis trap
Spokes typically use mGRE as well; if they used p2p GRE, they would only connect to the hub, but the scenario does not indicate this.
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 300-410 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 300-410 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.
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Device Management — study guide chapter
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Device Management practice questions
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FAQ
Questions learners often ask
What does this 300-410 question test?
Device Management — This question tests Device Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The spokes are missing the 'ip nhrp nhs' command to point to the hub, preventing registration and resolution of spoke-to-spoke addresses. — For spoke-to-spoke tunnels to form, NHRP must be configured to allow spoke registration and resolution. The hub configuration includes 'ip nhrp map multicast dynamic', which allows spokes to register, but spokes must also have 'ip nhrp nhs' pointing to the hub. If R2 and R3 do not have NHRP server configuration, they will not register, and thus cannot learn each other's addresses. The root cause is missing NHRP NHS configuration on the spokes.
What should I do if I get this 300-410 question wrong?
Identify which 300-410 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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