I have a lab I’m trying to work out where there is a router connected to an ISP with 2 links (10.20.30.0/24 10.20.40.0/24) over serial connection. The ISP has 3 loopbacks, 1 which is simulating a webserver, the other 2 simulating DNS servers. What the question is:
SLA probes should be implemented to monitor DNS servers (simulated by loopbacks on the ISP router, with addresses 184.108.40.206/24 and 220.127.116.11/24) to maintain connectivity to a web server (simulated by a loopback with address 18.104.22.168/24).
I assume that is a DNS server goes down then it will change from 10.20.30.0 to 10.20.40.0 but how do I monitor 1 loopback and change the link of the ISP?