What are GitHub's IP addresses?

I’m not sure if it is something to be concerned about, but when I tried to run a git push command today, it told me

Warning: Permanently added the RSA host key for IP address '64:ff9b::c01e:ff70' to the list of known hosts.

So, just like I know we should check SSH key fingerprints when connecting for the first time, should we also check IP addresses? Could I get man-in-the-middled if I don’t? Where can I see the list of GitHub IP addresses?

I’m assuming the DNS server resolves to the proper IP address, but what if the DNS server is hacked?

(sidenote: No GitHub-flavored Markdown in GitHub forums?)

After thinking for a bit, I suppose a man-in-the-middle wouldn’t know the GitHub private keys, so the SSH connection wouldn’t work if that was the case?