Since I run multiple sites on various servers I face lot of problems, which includes non availability of sites. Sometimes it’s hard to tell whether the problem lies with the server or with the ISP (Internet Service Provider). Even you could face a similar problem when you are not able to access a particular site.
Don’t worry because DownOrNot has a simple but effective solution for your simple yet complex problem. They try to access the site provided by you with their servers located across the globe to find whether the site is UP or DOWN. If they don’t get response within 4 seconds, they consider the site to be DOWN.
I’m a happy man because every time I find my site DOWN I don’t have to ask my friends to check.