My understanding from the Site24x7 support staff is sustained alerting for URL monitors is limited to the page response monitors (illustration below). It would be more useful to provide sustained alerting for all URL monitors (e.g.: HTTP 400 and above, DNS, socket timeout, etc.). This would allow automation to filter through valid alerts while ignoring insignificant, short term blips. I previously used a five minute sustained "observation" mode with a competitor's product. That worked quite well, ensuring only valid alerts were actioned. I'd love to see a high caliber product like Site24x7 be more helpful on this front.