Internet Information Services (IIS, formerly Internet Information Server) is an extensible web server created by Microsoft for use with Windows NT family.[2] IIS supports HTTP, HTTPS, FTP, FTPS, SMTP and NNTP. It has been an integral part of the Windows NT family since Windows NT 4.0, though it may be absent from some editions (e.g. Windows XP Home edition), and is not active by default.
History[edit]
The first Microsoft web server was a research project at the European Microsoft Windows NT Academic Centre (EMWAC), part of the University of Edinburgh in Scotland, and was distributed as freeware.[3] However, since the EMWAC server was unable to handle the volume of traffic going to Microsoft.com, Microsoft was forced to develop its own web server, IIS.[4]
Almost every version of IIS was released either alongside or with a version of Microsoft Windows:
IIS 1.0 was initially released as a free add-on for Windows NT 3.51.
IIS 2.0 was included with Windows NT 4.0.
IIS 3.0, which was included with Service Pack 2 of Windows NT 4.0, introduced the Active Server Pages dynamic scripting environment.[5]
IIS 4.0 was released as part of the "Option Pack" for Windows NT 4.0. It introduced the new MMC-based administration application.
IIS 5.0 shipped with Windows 2000 and introduced additional authentication methods, support for the WebDAV protocol, and enhancements to ASP.[6] IIS 5.0 also dropped support for the Gopher protocol[7]
IIS 5.1 was shipped with Windows XP Professional, and was nearly identical to IIS 5.0 on Windows 2000.
IIS 6.0, included with Windows Server 2003 and Windows XP Professional x64 Edition, added support for IPv6 and included a new worker process model that increased security as well as reliability.[8]
IIS 7.0 was a complete redesign and rewrite of IIS, and was shipped with Windows Vista and Windows Server 2008. IIS 7.0 included a new modular design that allowed for a reduced attack surface and increased performance. It also introduced a hierarchical configuration system allowing for simpler site deploys, a new Windows Forms-based management application, new command-line management options and increased support for the .NET Framework.[9] IIS 7.0 on Vista does not limit the number of allowed connections as IIS on XP did, but limits concurrent requests to 10 (Windows Vista Ultimate, Business, and Enterprise Editions) or 3 (Vista Home Premium). Additional requests are queued, which hampers performance, but they are not rejected as with XP.
IIS 7.5 was included in Windows 7 (but it must be turned on in the side panel of Programs and Features) and Windows Server 2008 R2. IIS 7.5 improved WebDAV and FTP modules as well as command-line administration in PowerShell. It also introduced TLS 1.1 and TLS 1.2 support and the Best Practices Analyzer tool and process isolation for application pools.[10]
IIS 8.0 is only available in Windows Server 2012 and Windows 8. IIS 8.0 includes SNI (binding SSL to hostnames rather than IP addresses), Application Initialization, centralized SSL certificate support, and multicore scaling on NUMA hardware, among other new features.
IIS 8.5 is included in Windows Server 2012 R2 and Windows 8.1. This version includes Idle worker-Process page-out, Dynamic Site Activation, Enhanced Logging, ETW logging, and Automatic Certificate Rebind.
IIS 10 is included in Windows Server 2016 and Windows 10. This version includes support for HTTP/2.[11]
All versions of IIS prior to 7.0 running on client operating systems supported only 10 simultaneous connections and a single website.
Microsoft was criticized by vendors of other web server software, including O'Reilly & Associates and Netscape Communications Corp., for its licensing of early versions of Windows NT; the "Workstation" edition of the OS permitted only ten simultaneous TCP/IP connections, whereas the more expensive "Server" edition, which otherwise had few additional features, permitted unlimited connections but bundled IIS. It was inferred that this was intended to discourage consumers from running alternative web server packages on the cheaper edition.[12] Netscape wrote an open letter to the Antitrust Division of the U.S. Department of Justice regarding this distinction in product licensing, which it asserted had no technical merit.[13]
