Total Uptime’s DNS failover works by constantly monitoring at least two servers using any number of fully customizable monitoring tests that you create. It allows you to send traffic to those servers via one of two methods. (1) You can use Round Robin to send traffic to all of your available servers, or (2) you can send traffic to the servers in the order you list them (called the Sequential method) and failover, one-by-one, as they become unavailable. This could be referred to as an active/passive or active/standby method.
As our system monitors, it keeps track of test failures. When the threshold (retries) has been met as specified in the monitor configuration dialog, it makes an automatic and immediate DNS entry change for that ‘A’ record that you have failover enabled for. This stays in effect until the server is back online UNLESS you have unchecked the auto-rejoin feature, in which case the DNS Failover Service will not automatically update the A record to start sending traffic back to that server.
If you need any assistance with configuring DNS Failover, please create a support case. We’re here 24×7 to help!