a record ?ranking?

[Daniel J Wendell]

Is there any way to ?rank? A records - kindof like the way MX records are
setup. In other words - if I had two servers setup as www.123.com and I
wanted to make sure that the user always went to the first one, but if and
only if that server is unavailable they would be sent to server 2.

www        IN    A    999.999.100.1
www        IN    A    999.999.100.2

I want the users to always go to 1
but if 1 is completely unavailable go to 2

thanks
dan