Record DNS for 2 static ip - fault tolerance

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http://serverfault.com – i've a web server in a DMZ reachable from 2 different public static ip addresses provided by 2 different internet connection by 2 different ISPs. I want to create a record let's say "myserver.contoso.com" that load balance the two ip in normal situation (round robin). The main goal however is that the server is still reachable if one internet uplink (so one public static ip) goes down. What can i do to achive this? ()