If your website goes down, you want to be the first to know. Make it obvious when there’s a problem by hooking up a big alarm light to a Tessel, which will ping your website every few seconds to check for trouble.
Continuously off: all is well
Continuously on: website being monitored is down
Two-second bursts (on or off): system error; monitoring isn’t working (reset the Tessel)
For more detail: Website Down Alarm using Tessel board