After running a test, AlertSite will automatically sort which domain is outside or within your domain (In-Domain and Out-Of-Domain) which you can see when you View Run or Waterfall.
(Outlined here https://support.smartbear.com/alertsite/docs/dashboards/monitor-runs/waterfall.html)
However in some case you may have resources that don't sit on the exact same domain that the monitor is running against. So for example a monitor on sales.testsite.com may pull in references from a parent site testsite.com or a delivery network cdn.testsite.com.
Currently Alertsite doesn't see these as being In-Domain so when you are looking at filtering you end up getting a mixed collection that doesn't easily aid you in seeing the correct information.
My idea is to allow account/sub-account wide URL's to be defined as In-Domain, additionally a monitor level could also be useful too.