Cisco Exam 300-730 Topic 8 Question 67 Discussion

The DMVPN-Tunnel Health Monitoring and Recovery (Backup NHS) feature allows you to control the number of connections to the Dynamic Multipoint Virtual Private Network (DMVPN) hub and allows you to switch to alternate hubs in case of a connection failure to the primary hubs. https://www.cisco.com/en/US/docs/ios-xml/ios/sec_conn_dmvpn/configuration/15-2mt/sec-conn-dmvpn-backup-nhs.html#:~:text=The%20DMVPN%2DTunnel%20Health%20Monitoring%20and%20Recovery%20(Backup%20NHS),failure%20to%20the%20primary%20hubs.

Backup NHS, or Next Hop Server, is a feature of DMVPN Phase 3 that allows a spoke router to switch to an alternate hub when the primary hub is unreachable. This is accomplished by using a secondary IP address for the hub router, which is used as the next hop for any traffic sent by the spoke router to the hub.