How It Works
Three things have to take place for an end users to be a see a new IP address as a result of SiteBacker-initiated DNS changes: (1) detection time + (2) authoritative propagation + (3) recursive expiration:
(2) Authoritative Propagation: 0 - 10 minutes. (Propagation is variable and usually under 1 minute throughout network but can be higher during periods of high activity.)
(3) Recursive DNS expiration (TTL value of pool records. Configurable by customer. 60 seconds to 900 seconds, usually.)
Probe Interval: 2 minutes (User Configurable)
Pool Record: 2 minutes (User Configurable)
That means the time to failover is 2 minutes (probing) + 1 minute (additional processing) + authoriative propagation (0 - 10 minutes) + recursive expiration (0 - 2 minutes).
So a failover can take 15 minutes to be seen by the end user--though the most common time would be 2-6 minutes.
Please note that values like agent threshold do not affect your failover time in any significant way. If you have a probe interval of 30 seconds, all selected agents probe every 30 seconds.