I am setting up a second redundant web server to give us fail over protection if our primary web server/hosting company go down. The secondary web server is located at another data center on the other side of the country. If our primary server goes down I want all web page requests to immediately get routed to the back up server, but I'm not sure how to get this to happen. The DNS a record for the domain specifies the specific IP address of the primary web server. If I have to change the DNS to point to the secondary server, it will take too long to propagate, and we will potentially go down for up to 48 hours for some users.
Is there any way to set up DNS A records similar to MX records, so that it has multiple entries and tries each one in order of precedence and stops at the first one that works?
What other solutions are there for this problem? How are other people approaching this?
Any advice is greatly appreciated.