I'm trying to configure GitHub with my naked domain.com (APEX in GitHub) and www.domain.com.
I have username.github.io working OK.
My A record is pointing to 192.30.252.153 and 192.30.252.154.
I then have two CNAME records set:
www.domain.com→domain.comio.domain.com→username.github.io
This configuration, however, is not working.
Accessing domain.com results in a 404 on GitHub. Meanwhile, accessing www.domain.com results in an ERR_NAME_NOT_RESOLVED.
Existing documentation is confusing and there's no clear way of configuring things end-to-end.
Can someone tell me what I'm missing?

