DNS resolving is still enabled on some builders.

Builds inside mock should have 0 network access outside loopback interfaces IMO. That is expectation for all Fedora, CentOS and RHEL builders.

I used https://github.com/junaruga/report-build-env-dns as it is minimal reproduction equivalent of what will then happen with Ruby package build-time tests.

These all builds should fail:
https://kojihub.stream.rdu2.redhat.com/koji/taskinfo?taskID=3427094
https://kojihub.stream.rdu2.redhat.com/koji/taskinfo?taskID=3427091

However some passed. That's not correct. It's not even consistent WRT to which arches failed.

If a build passes it means it was able to resolve IP addresses for the hostname of a remote server. We don't want that to happen ideally.