hardMultiple ChoiceObjective-mapped
300-410 Practice Question: A DMVPN network uses EIGRP as the routing protocol
A DMVPN network uses EIGRP as the routing protocol. After redistributing a static route into EIGRP on the hub, spoke-to-spoke tunnels fail to form. Hub configuration:
router eigrp 100
redistribute static metric 10000 100 255 1 1500 !
ip route 10.0.0.0 255.0.0.0 Null0 Spoke1# show dmvpn Interface: Tunnel0, IPv4 NHRP Details
Type:Spoke, NHRP Peers:2,
# Ent Peer NBMA Addr Peer Tunnel Addr State UpDn Tm Attrb
1 192.168.1.1 10.1.1.1 UP 00:01:00 D 2 192.168.1.2 10.1.1.2 UP 00:00:30 D
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 static Null0 route is redistributed, causing spokes to send traffic to the hub instead of directly to other spokes.
The static route to Null0 for 10.0.0.0/8 is redistributed into EIGRP, causing all spokes to learn a summary route pointing to Null0 on the hub. This blackholes traffic destined to other spokes, preventing dynamic spoke-to-spoke tunnel establishment. The fix is to use a more specific static route or filter the Null0 route from redistribution.
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 static Null0 route is redistributed, causing spokes to send traffic to the hub instead of directly to other spokes.
Why this is correct
The Null0 route blackholes traffic, preventing spoke-to-spoke communication.
- ✗
The EIGRP metric is too low, causing the route to be preferred over NHRP.
Why it's wrong here
Metric does not affect NHRP; the issue is the route itself.
- ✗
The DMVPN tunnel is misconfigured with mismatched authentication.
Why it's wrong here
Tunnel is up; authentication is not the issue.
- ✗
The redistribute static command is missing the route-map to set the next-hop.
Why it's wrong here
Missing route-map does not cause spoke-to-spoke failure; the Null0 route is the problem.
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
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.
About these practice questions
This 300-410 question is part of Courseiva's 1,966-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.