GitLab Pages what is considered a custom domain?

Hey I’m trying to setup pages for a self-hosted GitLab instance. I found the documentation for pages administration a bit confusing when it comes to custom domains. Would the following example count as a custom domain?
gitlab-pages: (would used the * for dns wildcard)

* as a two-level sub domain will not work for TLS wildcard certificates, in case you are using Let’s Encrypt.

It is recommended to use a different domain for the pages domain, e.g. where the GitLab server gets its DNS entry, and where the Pages entries are configured.

GitLab Pages administration | GitLab provides more details on the configuration requirements.

Ok It looks like my original domains from the documentation would work. But this doesn’t answer if this would fall under a custom domain. Would it be better if the urls be like this?
gitlab pages:

Based off the previous comment would a secondary IP need to be used?