When creating a new monitor, you'll be able to optionally set a Confirmation period on the monitor.
Confirmation period defines the amount of time that a monitor must be down for in order to mark your monitor as down. If your monitor recovers withini this confirmation period, the window is reset and you won't be notified of any downtime.
Let's say you have a HTTP monitor that checks every 15 minutes and you have a confirmation period of 5 minutes. Your monitor is UP until 13:00 and then goes down instantly. We'll check your monitor every minute, one at 13:01, 13:02, 13:03, 13:04 and 13:05.
Because your confirmation period was set to 5 minutes, all checks from 13:00 to 13:05 must be considered as DOWN for your monitor to be marked as DOWN at 13:05.
Tip: setting the confirmation period to Immediate start will disable this feature.
When you have a website that's going down and coming up in quick succession, this is quite unstable and could have an impact on users. In this context, your website is technically up, only when your website hasn't been going up/down in quick succession for a while could you consider your website as down.
The confirmation period feature allows you to esentially reduce the noise and notifications that you receive for incredibly short periods of downtime.
This feature works great when configured alongside the recovery period to improve the accuracy of monitoring.