Web analytics firm Netcraft (www.netcraft.com) is expanding on its web server survey by offering a dataset of the most active sites, giving a truly global analysis of web hosts.

The firm explains that each website that is found on its monthly web server survey can be attributed to a hosting location using reverse DNS and IP address delegation information.

This information is then compiled into a list of parent companies, revealing a league table of companies of which control the largest number of websites.

The report comes on the heels of Netcraft’s most recent web server survey for April, which saw Apache as the most popular web server with a total of more than 106 million sites, followed by Microsoft-IIS’s 67 million and QQ’s nearly 29 million.

The information is produced for many different metrics based on the number of hostnames, active sites and IP addresses used by the company.

Displayed in an Excel spreadsheet, the data uses different filters and selections to provide a full analysis by country, operating system, and web server software, as well as the option of inspecting absolute numbers, rate of growth and technology deployed at individual companies.

Each spreadsheet release includes a full rundown of web host trends the most recent four months, as well as six and twelve month views.

For instance, February 2009 dataset saw Microsoft as the top hosted parent company with 7,578,608 active sites, followed by Google with 6,220,058 active sites and MySpace.com with 4,504,403 active sites.

However, Netcraft does point out some limitations to this dataset. For one, it does not provide the names of the underlying website hostnames.

Those interested in site details including hostnames, hosting location, operating system, web server software, traffic and content technologies can purchase this data separately.

Additionally, the firm says it only includes sites found by its monthly web server survey, which found over 200 million hosts running internet websites in February 2009.

Finally, since a reverse DNS server for the network must be supplied in order to attribute a site to a web host, some sites are listed as having an unknown web host in the case that a reverse DNS server is not provided.