hardMultiple ChoiceObjective-mapped
300-410 DMVPN Phase 2 Practice Question
In a DMVPN Phase 2 network with EIGRP, R1 (hub) and R2 (spoke) are configured with EIGRP stub leaking. R2 is a stub router with 'eigrp stub connected summary'. R3 (another spoke) is not a stub. R2's loopback 10.0.0.1/32 is not reachable from R3, even though R2 advertises it via EIGRP. What is the root cause?
⚠ Common exam trap
Candidates often overlook the necessity of NHRP in DMVPN Phase 2 when focusing on EIGRP stub configuration. Even with proper stub leaking, a spoke without NHRP will prevent other spokes from routing to its networks.
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
✓
NHRP is not configured on R2, preventing route advertisement.
In DMVPN Phase 2, EIGRP stub leaking allows the hub to advertise spoke routes to other spokes, but the next-hop remains the spoke's tunnel IP. For R3 to install the route to 10.0.0.1/32, it must have an NHRP mapping to reach R2's tunnel IP. Without NHRP configured on R2, R3 cannot resolve the next-hop, making the route unreachable. The EIGRP stub configuration is correct, but NHRP is missing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
R2 is configured with 'eigrp stub receive-only', which prevents it from advertising any routes, including connected ones.
Why it's wrong here
Incorrect. The stem explicitly states that R2 is configured with 'eigrp stub connected summary', not 'receive-only'. 'Receive-only' would contradict the given configuration.
- ✗
R3 has a distribute-list filtering the prefix 10.0.0.1/32 from EIGRP updates.
Why it's wrong here
Incorrect. There is no evidence of a distribute-list on R3; the question does not mention any filtering. The issue is likely network-layer reachability, not filtering.
- ✗
R2's loopback is not in the same EIGRP autonomous system as the tunnel.
Why it's wrong here
Incorrect. The stem states that R2 advertises the loopback via EIGRP, meaning it is in the same autonomous system. If it were not, the route would not be advertised at all.
- ✓
NHRP is not configured on R2, preventing route advertisement.
Why this is correct
Correct. Without NHRP on R2, R3 cannot resolve R2's tunnel IP to a physical address, so the route to 10.0.0.1/32 remains unreachable despite being advertised.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
EIGRP Stub Routing
EIGRP stub routing is a feature that restricts a router from learning routes from neighbors and limits the routes it advertises, improving network stability and reducing resource usage in remote or spoke locations.
Key term
DMVPN Phase 2
DMVPN Phase 2 is an advanced Cisco routing technology that allows spoke routers to communicate directly with one another without sending traffic through a central hub, using dynamic routing protocols and multipoint GRE tunnels.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.