The other day I was chatting with Mr. X and while we were talking he said:
And I was wondering because this guy is a coder and I was thinking he knows everything. Well, turned out he did not know about uptimerobot.com.
It’s a free website where you enter all your important domains. (You even can enter domains that are not yours!) If I remember right the free account allows you to enter up to 50 domains. Then their system checks if the domain is online every 5 minutes. In case your domain is off, you get an instant mail. Also if your domain comes back you will get informed. If you go for a paid account then the system checks every minute or so. And the best: They don’t send you any spam! So gogogo!
P.S. Inside the dashboard there are some nice graphs that show all data like up- and downtime.