I have a 5 terminal servers that are currently accessed by approximately 300 users. They're currently accessing them via outside ip addresses. I have 2 different ip addresses for each terminal server, each corresponding to a different internet service provider. I would like to set up a dns for each terminal server such that the users will not have to deal with ip addresses and I can just change the a records for the host names in the background if there's a problem with the isp; however, I'd like the change to be instantaneously instead of having to wait for the changes to propagate for 12-24 hours. Any ideas?