According to results from the Netcraft May 2014 survey, which received responses from 975,262,468 sites, Microsoft's IIS and Azure are both threatening Apache's market lead. In fact, Microsoft is now 4.1 percent behind Apache.
"Microsoft gained nine million additional sites this month, increasing its market share by a further 0.37 percentage points. Meanwhile, despite gaining 4.3 million sites, Apache's market share fell by 0.18 points. Although Apache still leads with 37.6% of all sites, Microsoft is now just 4.1 percentage points behind. Apache has been the most commonly used web server for more than 18 years, but this is the closest Microsoft has ever been to threatening this position."
The survey also revealed that nearly seven million of the month's new websites are now using Microsoft IIS. Roughly eleven thousand of these new sites are hosted on Microsoft Azure, giving Microsoft the distinct title of being the largest Windows hosting company. The majority of these new IIS sites powered by Microsoft Azure are hosted in the United States, while a third of them are being hosted in the North Central US Azure region.
Apachelounge.com, which is a fantastic resource for obtaining help and resources for running Apache on Windows, has also recently made the move to Microsoft IIS. This site has had a long history of running their site from an Apache web server running Windows Server 2008. They are now on IIS 8.5 running Windows Server 2012.
Apache may be the most commonly used web server for nearly two decades, but Microsoft is coming ever so close to threatening its position.