If the filesize check is selected, on every check our monitoring agent will compare the size of the downloaded page with a value that is cached in the WebSitePulse.com database. If the values are not equal you will be alerted respectively. The filesize value is cached right after you update the target configuration and will stay the same until the target is updated again. That is why to avoid false positives, you will have to re-save your monitoring configuration every time you update your site.
This article applies to the Performance, Full-page and the Transaction monitoring services only.
Frequently asked questions