Netriplex's DNS failover works by constantly monitoring at least two servers.
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 and failover,
one-by-one, as they become unavailable.
As our system monitors, it keeps track of test failures. When the threshold
has been met, 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.