Heading the table for April with only two failed requests from any of the performance monitors during the month was Rackspace. Rackspace provides managed and cloud hosting from nine datacentres in the U.S., the U.K. and China. Rackspace frequently features in Netcraft's top ten most reliable hosting companies, having appeared five times in the last year.

Second most reliable this month was Qube, a London-based hosting company which also has datacentres in New York and Zurich. Qube provide managed hosting, managed colocation and cloud hosting for a wide variety of customers, particularly in the areas of finance and new media. Although Qube has previously appeared in the top ten, this is the first time the hosting company has made it to the top three.

The third most reliable hosting company in April was Netcetera. Netcetera experienced the same number of failed requests as Qube, but had a longer average connection time. Netcetera provides a wide range of colocation, hosting and cloud services to customers throughout the world.

Five of the top ten sites this month were running on Linux, two were running on FreeBSD, and one on Windows. Rackspace's site, which performed best this month, is hosted on F5 Big-IP.

Netcraft measures and makes available the response times of around forty leading hosting providers' sites. The performance measurements are made at fifteen minute intervals from separate points around the internet, and averages are calculated over the immediately preceding 24 hour period.

From a customer's point of view, the percentage of failed requests is more pertinent than outages on hosting companies' own sites, as this gives a pointer to reliability of routing, and this is why we choose to rank our table by fewest failed requests, rather than shortest periods of outage. In the event the number of failed requests are equal then sites are ranked by average connection times.

Information on the measurement process and current measurements is available.