Protect your domain name from expiring
We sometimes receive frantic support calls about a web site that “is completely down.” We do a little checking and discover that the web site is fine, but the domain name registration has expired. In some cases, the registration expired so long ago that the registration has been completely deleted (and in one case, re-registered by a porn site).
This problem is almost always caused by invalid contact e-mail addresses in the domain name record. Most registration agencies send renewal notices by e-mail to the billing contact or administrative contact associated with the domain name. If those e-mail addresses are no longer valid, you can't receive the renewal notice, your domain registration expires, and your domain name is “turned off”. In some cases, you may even lose your rights to the domain name entirely.
To avoid this scenario, you should check your web site frequently, even if you haven't made any recent changes. Check the information associated with your domain name to make sure that all of the information is still valid. If it is not still valid, update it. You can view your domain name record by using the WHOIS lookup functionality of almost any domain registrar.