How come Red Hat hangs on startup?

From the Tips-HOWTO:

This is a fairly common problem, almost to the point of being a FAQ. I don't know if RedHat has fixed this bug in their distribution, but you can repair it yourself. If you look in your /etc/hosts file, you will find it looks something like:

127.0.0.1               localhost       yourbox

When sendmail starts, it does a lookup on your hostname (in this example, yourbox). It then finds that the IP for yourbox is 127.0.0.1, sendmail doesn't like this, so it does the lookup again. It continues with this for a while until it eventually gives up and exits. Fixing the problem is extremely easy, edit your /etc/hosts file and change it to something like this:

127.0.0.1               localhost
10.56.142.1             yourbox

The IP address of yourbox does not matter -- as long as it starts with 10.....