Network address Translation

2 options here depending upon what is accessible from the GTM, public NAT or private IP.

1. Use the public ip when setting up the virtual server so it will return the public ip to the resolver, but also run the health check thru the NAT.

or

2. Use the public ip when setting up the virtual server so it will return the public ip to the resolver, but configure a custom monitor for the virtual server and use the 'destination' option to set the internal ip address of the server to run the health check against.