300-410 Layer 3 Technologies Practice Question
A network engineer is troubleshooting a DMVPN Phase 3 deployment on a Cisco IOS XE router. The hub router is configured with 'ip nhrp redirect' and the spoke routers with 'ip nhrp shortcut'. However, spoke-to-spoke traffic is still traversing the hub. Which action should the engineer take to enable direct spoke-to-spoke communication?
⚠ Common exam trap
The trap here is assuming that enabling NHRP redirect and shortcut alone is sufficient, without verifying that routing and NHRP resolution are correctly configured.
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
✓
Ensure that the spoke routers have a route to the spoke networks via the tunnel interface and that NHRP resolution is working.
Spoke-to-spoke shortcuts in DMVPN Phase 3 require that spokes have a route to the destination network via the tunnel interface and that NHRP resolution succeeds. The hub uses NHRP redirect to tell the spoke that a better path exists, and the spoke uses NHRP shortcut to install a direct entry. Without these, traffic continues through the hub.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure 'ip nhrp network-id' with the same value on all routers.
Why it's wrong here
The NHRP network ID must match for routers to form an NHRP network. However, if it were mismatched, NHRP resolution would fail entirely, and the tunnel would not come up. Since the tunnel is up and traffic flows through the hub, the network ID is likely correct. The problem is more specific to shortcut establishment.
- ✗
Configure 'ip nhrp map multicast dynamic' on the hub.
Why it's wrong here
This command enables the hub to dynamically learn multicast mappings for spokes, which is necessary for multicast traffic but does not enable spoke-to-spoke unicast shortcuts. Without the correct NHRP resolution and shortcut configuration, unicast traffic will still go through the hub.
- ✓
Ensure that the spoke routers have a route to the spoke networks via the tunnel interface and that NHRP resolution is working.
Why this is correct
For DMVPN Phase 3 shortcuts to work, spokes must have a route to the destination spoke network pointing to the tunnel interface, and NHRP must resolve the destination NBMA address. The hub uses redirect messages to inform spokes of a better path, and spokes use shortcut to install a direct NHRP entry. Without proper routing and NHRP, shortcuts fail.
- ✗
Enable 'ip nhrp authentication' on all routers.
Why it's wrong here
NHRP authentication is used to secure NHRP messages between routers. While it is good practice, it does not affect the establishment of spoke-to-spoke shortcuts. The issue is likely related to routing or NHRP resolution, not authentication.
Go deeper
Related to this question
Learn chapter
DMVPN and FlexVPN Technologies
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.
Key term
DMVPN Phase 3
DMVPN Phase 3 is a Cisco networking technology that allows branch offices to connect directly to each other without always going through a central hub, but with smarter routing that lets the hub control the traffic paths more efficiently.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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.