Err, they do. Here's how to set it up: These balance the load, and if one machine is down, any browser which handles multiple A records properly will still fail over to the other machine.
www IN CNAME www1.av8.com. IN CNAME www2.av8.com.
www1 IN A 198.3.136.144 IN A 208.156.100.250 www2 IN A 208.156.100.250 IN A 198.3.136.144
This also assigns more than one CNAME to the www label, which is a bad idea. You can force BIND (8.x) to allow it via "multiple-cnames yes", but you'll probably get behavior you don't want since nameservers on the net will cache just one of the CNAMEs (this isn't a problem in the example above, but most people don't use the same set of addresses for www1, www2, and so on). The BIND configuration file guide says: ---------------------------------------------------------------------- multiple-cnames: If yes, then multiple CNAME resource records will be allowed for a domain name. The default is no. Allowing multiple CNAME records is against standards and is not recommended. Multiple CNAME support is available because previous versions of BIND allowed multiple CNAME records, and these records have been used for load balancing by a number of sites. ---------------------------------------------------------------------- Just use multiple A records. -- John Caruso, Director, System/Network Administration CNET: The Computer Network Email: caruso@cnet.com 150 Chestnut Street Phone: 415.395.7805 x1310 San Francisco, CA 94111 Fax: 415.623.2458