Let's say you have an IDX site site all set up by an IDX vendor
and the website address is something like:
But you purchased a really cool domain name:
Wouldn't you rather have potential sellers and buyers using your really cool domain name instead of the not-really-cool utilitarian address provided by your IDX vendor?
Let's fix that...
In this example, GoDaddy is the DNS provider. The same principles apply to most any DNS host. Login and navigate to the section where you manage your DNS records.
Set up a Forwarding record to send traffic from besthomefinders.com to www.besthomefinders.com. This makes sure all traffic to your site ends up having the www prefix.
Now, set up a CNAME record that directs all traffic with a www prefix to the johndoe.jiffywebsites.com IDX site. When you set up a CNAME record like this, the user's browser will display www.besthomefinders.com as your website address.
Give things about an hour to propagate through the record servers on the Internet. It might even happen super fast if things are happening super fast at the moment!