Hypothetically speaking of course, let’s assume you forget to renew a domain name. And suddenly that domain’s email is not working. And then you notice the site is down. The next step is, logically speaking, to panic, followed by an attempt to figure out what the hell is going on. Which usually means restarting Apache. Which results in:
apache2: apr_sockaddr_info_get() failed for yourhost
Which is, wow, an exotic new error. If you see this it means that, even though Apache says its restarting, really its probably not. And now all your other sites are down. And, so, more panic. More panic for you.
Now that you’ve probably realized that the default domain name has expired, you will want to get Apache back up on a different, actually non-expired domain. Like this:
$ hostname actual-non-expired-domain-name.com
Alternatively if your hostname is set to something like “www”, probably you can change the default site in vhosts so that Apache can connect the hostname to the tld.
This is all hypothetical of course.