You can use an IPv6 address instead of the domain name in the URL field of your monitor if you choose, but remember, you have to use square brackets around the address and select IPv6 for your monitor's IP version. If you don't indicate IPv6 your monitor will generate errors when tested from checkpoints that do not support IPv6.

For example:

http://[2a01:5cc0:1:2::4]

Monitor URL field with IPv6 address in brackets