Can alerts be triggered only if a failures occur at more than one location?

Yes! This is possible using the Minimum Node Location configuration when creating an Alert.

If a minimum of two locations is selected, it would take two locations failing at least once within the Time Rolling Window for it to generate an alert. Since only one test runs at a time it would require two tests to fail. The consecutive selector will require two consecutive tests to fail within the window specified, if the consecutive selector is not used then any two failures within the specified window will result in an alert. I personally prefer the multi-location consecutive fail alerts because it rules out ISP issues and sometimes localized Internet issues while ‘usually’ ruling out multiple failed tests from a single location.

The retry on failure always occurs on the same node as it is performed within the same session; it does not kick off a newly scheduled test somewhere else.

Random sequence is truly random, it will happen in different locations much of the time but there is no specific guarantee of a round-robin type of scenario.

Here are a couple scenarios:

Test 1:

Alert email received:

Test 2 (consecutive not selected)

Alert email received