350-401 Question 521
Single answerYour organization is implementing a DMVPN (Dynamic Multipoint VPN) solution for secure communication between multiple branch offices. You are configuring Next Hop Resolution Protocol (NHRP) on the DMVPN hub router. Which NHRP configuration command should you use to allow the hub to provide the correct public IP address of the spoke routers to other spokes when they request it?
- A
ip nhrp map multicast dynamic
- B
ip nhrp network-id
- C
ip nhrp nhs
- D
ip nhrp map
Show answer and explanation
Correct answer: A
Explanation
The 'ip nhrp map multicast dynamic' command is specific to DMVPN deployments and is used on the hub router to enable dynamic mapping of spoke routers' public IP addresses (NBMA addresses) to their private tunnel IPs using NHRP. This configuration is essential for facilitating spoke-to-spoke communication in DMVPN, as the hub must provide the necessary resolution information when spokes attempt to communicate directly.
- A. Correct.
This command is used to enable the hub to dynamically respond to NHRP requests with the public IP addresses of spoke routers. It is crucial for spoke-to-spoke communication in DMVPN.
- B. Incorrect.
This command is used to assign a unique network ID to the DMVPN network, ensuring that NHRP messages are processed only within that network. While important, it is not responsible for resolving spoke IP addresses.
- C. Incorrect.
This command is used to configure the hub as the NHRP server, allowing spokes to register with it. However, it does not handle the dynamic resolution of spoke IP addresses.
- D. Incorrect.
This command is used to manually map a spoke's public IP address (NBMA) to its private IP address. While useful in static configurations, it does not support the dynamic resolution needed in this scenario.