Feature: alternative link and recheck

Sometimes i have some false alarms. Motives:

• Bad connection.
• One mirror fails but the alternatives work.
• Some ISP block X domain but not all.
• etc.

Possible solutions to mitigate it:

• Alternative links like mirrors or proxy's to check so if any connects.
• Recheck after a short time. If a checks fails try it again X time later and after Y fails then alarm.
• Alert after Y fails with the time currently set. (Easiest option)

This way i can sleep a little bit better