Website Uptime Monitors Review – Choosing the Right One

For my sins, I work part-time for other hosting companies, and one of the most common misunderstandings I encounter is when someone will swear blind their website is down when the truth is that their ISP is just suffering some temporary routing problems.

Customers come in all shapes and sizes, and degrees of ability and understanding of how the internet works, and the more savy website owners now use some form of website monitoring to make sure that us naughty dishonest web hosting companies are playing our part in their success.

Some folks spend more on the website monitoring than the hundred quid a year they are prepared to spend on the website hosting itself – hosting that enables their business to rake in a small fortune (but that’ a rant for another day!). So read on to understand more about uptime and availability.

Uptime vs Availability

It is important to note that Uptime shouldn’t be confused with Availability. Just because a server is up, doesn’t necessarily mean it’s available. When your website appears to vanish, your first reaction (once the light headed feeling subsides) is usually to call or ticket your hosting company. Perhaps the least helpful answer you could ever get from them is “it must be you, it looks up from here”.

To the support tech, the server may well appear to be up – as he’s connecting to it from a point either within, or very close to the datacentre. However, from your home broadband connection, the server may well be unavailable. says my site is down so you’re lying

So, not content with the support desk’s answer, you go off and check your website using something like, and now feel vindicated because that site is also saying your site is down.

It’s still possible your site is actually up! Just because it isn’t reachable from Sydney, or Krakow, doesn’t mean your server is down. It just means it’s unreachable from those locations. In all likelyhood, the guy living next door, using a different ISP can see your website just fine.

So what’s going on?

The internet is a huge network of interconnected routing centres, all run by different private companies, all making money from the ISPs and hosting companies who connect to them. There may be several such routing centres between your PC and your website – even if both exist in the UK. For websites on the other side of the world you may have to go through a dozen or more routers to reach the destination server. Look at this traceroute from my UK ADSL provider to a site in Australia:

steves$ traceroute
traceroute to (, 64 hops max, 52 byte packets
1  vigor.router (  3.471 ms  0.766 ms  1.140 ms
2 (  40.787 ms  41.114 ms  40.805 ms
3 (  39.822 ms  39.817 ms  40.634 ms
4 (  41.135 ms  42.964 ms  42.726 ms
5 (  122.508 ms  122.379 ms  122.664 ms
6 (  122.670 ms  123.776 ms *
7 (  125.439 ms  122.700 ms  123.650 ms
8 (  127.839 ms  128.405 ms  128.088 ms
9 (  168.425 ms  154.335 ms  154.733 ms
10 (  159.328 ms  161.722 ms  178.160 ms
11 (  161.730 ms  161.648 ms  180.883 ms
12 (  159.796 ms  159.674 ms  160.928 ms
13 (  160.268 ms  160.342 ms (  160.994 ms
14  * * *
15 (  162.190 ms  159.797 ms (  159.880 ms
16 (  159.570 ms  159.518 ms  159.796 ms

Now, if I couldn’t open the website at, because a router in New York belonging to a third party is playing up, it’s hardly the fault of sydneyweb!

Routing storms and temporary outages

Routers use special routing protocols to calculate the most effective path along which to transmit your data packets to their destination. Sometimes, several key routers can start to hunt between paths, because upstream routers are experiencing a routing problem, maybe due to a failure, or high load. This can cause a condition where the path switching and packet loss lead to the apparent loss of connectivity between two stations.

Usually these issues last only a few minutes, but they can be more serious and last hours, or require manual intervention. These events are not uncommon, and it is for this reason that availability monitors like Pindgom, for example, are not the best choice for determining whether your server has failed!

So which monitor service should I use?

OK, so there are two things you need to know. The first is whether your server is really up – the other is how available it is.

Testing if your webserver is really up

The monitor you use for this should be a high level protocol test, such as a http page that relies on PHP and MySQL. It should also be using a monitoring node that is close to your web server in terms of the number of hops (each line in the traceroute above is a hop) – ideally in the same datacentre, or at least the same city! You don’t want a routing problem here, as that’s just going to confuse the issue if you choose a monitoring service that’s thousands of miles away…

Testing your availability

This is a different issue. Here you want to test access to your website from as many different locations as possible, and log the results. Availability testing is really about seeing how well the whole world can see your website. This is where you will see the short term drop outs – often from locations far, far away, but it can help you determine if there is a persistent problem from various locations.

The Monitors

I list three that I have had direct experience of here. There are of course dozens more – FREE and PAID services. Allows you to set up monitors for simple (ping) and complex tests (http) from a range of nodes around the world. Tests are only carried out from a single node, so this service is probably better geared to uptime monitoring. – FREE (for now). Allows simple (ping) and complex tests (http). All tests are conducted from their currently three nodes, which are US based, so this service is probably better for availability checking. – FREE and PAID services. The big daddy in many ways, Pingdom has over a dozen nodes around the world, and allows monitoring every minute. However, Pingdom does not allow you to choose which monitoring stations to use for the tests – using all of them by default, meaning it’s pretty useless as an uptime check. However, is is still perhaps the best availability monitoring tool.


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