hardMultiple ChoiceObjective-mapped
300-410 Practice Question: DMVPN spoke-to-spoke tunnel is not forming…
DMVPN spoke-to-spoke tunnel is not forming between two spokes. Hub router R1 has the following relevant configuration: interface Tunnel0 ip address 10.0.0.1 255.255.255.0 ip nhrp network-id 1 ip nhrp map multicast dynamic ip ospf 1 area 0 tunnel source GigabitEthernet0/0 tunnel mode gre multipoint Spoke R2 shows: show dmvpn Legend: Attrb -> S: Static, D: Dynamic, I: Incomplete Interface: Tunnel0, IPv4 NHRP Details Type:Spoke, NHRP Peers: 1 # Ent Peer NBMA Addr Peer Tunnel Add State UpDn Tm Attrb 1 192.168.1.1 10.0.0.1 UP 00:10:00 D Spoke R3 shows similar, but no spoke-to-spoke tunnel. 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
✓
Missing ip nhrp redirect on hub and ip nhrp shortcut on spokes.
Spoke-to-spoke tunnel requires NHRP redirect and shortcut route. Without ip nhrp redirect on hub and ip nhrp shortcut on spokes, traffic between spokes goes through hub. OSPF over DMVPN may also need mtu or ipsec issues. The correct fix is to enable NHRP redirect on hub and shortcut on spokes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Missing ip nhrp redirect on hub and ip nhrp shortcut on spokes.
Why this is correct
NHRP redirect triggers shortcut creation; without it, spokes always use hub.
- ✗
OSPF network type is broadcast; change to point-to-multipoint.
Why it's wrong here
Broadcast works with DMVPN; network type is not the primary cause.
- ✗
IPsec is not configured; DMVPN requires encryption.
Why it's wrong here
DMVPN can work without IPsec, though not recommended.
- ✗
The tunnel key is mismatched; configure tunnel key on all routers.
Why it's wrong here
Tunnel key is optional and not required for spoke-to-spoke.
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
Courseiva writes every 300-410 question from scratch — 1,966 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or 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.