The AllowKeepAlive property specifies whether Keep-Alive processing is permitted. If this property is set to TRUE, then a Connection: Keep-Alive header is appended to each response. Keep-alive connections provide one method by which you can improve performance for your Web application. In general, if both your application and the client have requested a persistent HTTP connection, IIS will continue to reuse the TCP/IP socket that was used to receive the initial browser request, instead of destroying it and creating a new socket for each and every additional request.
Client: Requires Windows XP Professional, Windows 2000 Professional, or Windows NT Workstation 4.0.
Server: Requires Windows Server 2003, Windows 2000 Server, or Windows NT Server 4.0.