How does Site24x7 always ensure the availability of its location agents during monitoring?
Site24x7 uses a preferred location recheck logic in the back-end to ensure the availability of all monitoring locations. This logic is only applied when you've disabled the option "Restrict monitoring within selected locations" in the Location profile configuration form. Every monitoring location is mapped to an alternate location. Whenever a primary location fails, Site24x7 automatically checks for the availability of primary location's mapped alternate location. If both the primary and its alternate location fails, Site24x7 then checks for an available location from the pool of monitoring locations configured by the user in the global account-level. This logic negates the need for unnecessary rechecks from random locations around the globe, when the primary location and associated locations are unavailable.
Let's consider a scenario where, "example.com" wants to monitor their domain from London, UK (its primary location). If the London monitoring location fails during a check; the preferred location logic is applied and Site24x7 immediately checks for the availability of the alternate monitoring location (preferably in the same geo-location, example- Edinburgh, Scotland, UK). For some reason, if this location also fails—then Site24x7 automatically checks for any available location from the pool of monitoring locations configured in the location profiles.
In a scenario, where you've configured only one location in your location profile, then the preferred location check logic will take into account the location, its alternate and all the locations within the same country code for re-check.
California location will always be excluded from the preferred location check logic.
For the preferred location check logic to be enabled, you just have to whitelist only those monitoring locations that are part of your global location profiles list.
IPv6 based locations also use the same preferred location check logic.