The above wiki article accomplishes the same result as editing the hosts file, it’s just generally easier for people to do.
So you have example.com hosted at your old host. Next you set up example.com here at dreamhost. Add it through the panel. This won’t have any effect on what website people get until you update the DNS entires with your registrar. Now you set up a mirror of example.com with example.dreamhosters.com.
The way this works is Dreamhost servers access the local DNS servers first - so when you go to examples.dreamhosters.com you get forwarded to example.com BUT, because the server that forwards you checks with the local DNS first you’re sent to the DH server hosting example.com
So it sounds strange, but it works - I’ve done it my self a number of times. Also, you could have signed up with “xyz.com” - it wouldn’t have effected or clashed, but it also doesn’t really make a difference.
Hope this all makes sense, I know there’s a lot of information to take in when you’re first getting started with a new host.
art.googlies.net - personal website