You need to specify a ServerName
directive in the Apache configuration like this:
ServerName yourdomain.com
or
ServerName localhost
Apache is not finding a ServerName so it is trying to make an educated guess at it. It has tried to figure it out from your hostname (the first message) and, not finding anything else it is assuming:
ServerName 127.0.0.1
i.e localhost (as per the second message).
This setting is not so important (apart from the error message) unless you have multiple Name Based Virtual hosts where it becomes crucial as it is the only way Apache can distinguish which host the client is trying to access.