Down or Not?

Wednesday, October 10th, 2012 | Jim Cheetham | Comments Off on Down or Not?

Here, this looks like a good joke … downornot.com is down!

Except of course, it isn’t down …

Or perhaps it is …

So, is DownorNot.com down, or not?

The problem here is that the meaning of “it” in the phrase “is it up or down?” is different each time. For the human, “it” is the service provided by the website, and that service is certainly non-functional (it looks like the website’s usage of the Google AppEngine service has gone over quota; and the developer who wrote their website didn’t anticipate this error. In this case, we would also anticipate that the service behind the website is also broken at the moment, whereas often a service and a website are separate). For isitup.org, “it” seems to be the initial contact with the site’s webserver, which is responsible for handling the HTTP conversation. For downforeveryoneorjustforme.com, “it” is the same thing, the webserver and not the application, but they are going a couple of steps further, following the redirections and noticing that the final page is delivered with an error status … and in this case, the failure of the application is reflected in the webserver status code. It doesn’t have to be.

Let’s ask isitup.org again, but this time go straight to www.downornot.com instead of just downornot.com …

So, if you are monitoring or testing a service, make very very sure that you understand what the question “Is it up?” is supposed to mean — and this depends on who is asking. Then, make very sure that you understand how your monitoring tools work, what you are asking them to do, and how to interpret them. Obviously, this isn’t as easy as it sounds …

If you are not careful, this is what you end up with :-