300-410 Layer 3 Technologies Practice Question
A network engineer is configuring a Cisco IOS XE router for DMVPN Phase 3. The hub router is configured with `ip nhrp map multicast dynamic` and `ip nhrp network-id 100`. The spoke routers are configured with `ip nhrp map` and `ip nhrp nhs`. The engineer wants to enable spoke-to-spoke communication without traffic traversing the hub after the initial resolution. Which additional command is required on the hub to support Phase 3 shortcut switching?
⚠ Common exam trap
The trap here is mixing up the roles of `ip nhrp redirect` and `ip nhrp shortcut`; the redirect is on the hub, while the shortcut is on the spokes.
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
✓
`ip nhrp redirect` on the hub tunnel interface.
DMVPN Phase 3 enables spoke-to-spoke communication with hub assistance. The hub uses `ip nhrp redirect` to send redirect messages to spokes when it detects that traffic between spokes could take a direct path. Spokes then use `ip nhrp shortcut` to create a direct tunnel. The hub must have `ip nhrp redirect` configured; otherwise, spokes never receive the redirect and continue to send traffic 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.
- ✓
`ip nhrp redirect` on the hub tunnel interface.
Why this is correct
In DMVPN Phase 3, the hub must be configured with `ip nhrp redirect` to inform spokes when a better path exists. When the hub receives a packet from a spoke destined to another spoke, it sends an NHRP redirect message to the originating spoke, prompting it to resolve the destination spoke's NBMA address directly. This enables spoke-to-spoke tunnels without traversing the hub for subsequent packets. Without this command, Phase 3 shortcut switching does not occur.
- ✗
`ip nhrp shortcut` on the hub tunnel interface.
Why it's wrong here
The `ip nhrp shortcut` command is configured on spoke routers, not the hub. It allows the spoke to use the redirect message from the hub to create a shortcut path to another spoke. On the hub, this command is not used and would not enable Phase 3 functionality. Therefore, it is incorrect for the hub configuration.
- ✗
`ip nhrp network-id 100` on the spoke tunnel interfaces.
Why it's wrong here
The `ip nhrp network-id` command must match on all routers in the DMVPN cloud to allow NHRP communication. While it is required, it does not enable Phase 3 shortcut switching. The scenario already indicates that the hub has network-id 100, and spokes likely have it configured. The missing piece for Phase 3 is the redirect command on the hub, not the network-id.
- ✗
`ip nhrp map multicast dynamic` on the spoke tunnel interfaces.
Why it's wrong here
The `ip nhrp map multicast dynamic` command is used on the hub to allow it to replicate multicast packets to all spokes dynamically. It is not used on spokes and does not enable Phase 3 shortcut switching. Spokes typically use `ip nhrp map multicast <hub-nbma>` to send multicast to the hub. This command is unrelated to the redirect mechanism required for Phase 3.
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.
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.