HTTP Keep-Alive on IIS 6.0

What is HTTP Keep-Alive?

A browser typically makes multiple requests in order to download an entire Web page. To enhance server performance, most Web browsers request that the server keep the connection open across these multiple requests, which is a feature known as HTTP Keep-Alives.

Without HTTP Keep-Alives, a browser that makes numerous requests for a page containing multiple elements, such as graphics, might require a separate connection for each element. These additional requests and connections require extra server activity and resources, decreasing server efficiency. The additional connections also make a browser much slower and less responsive, especially across a slow connection.

HTTP Keep-Alive feature on IIS 6.0

HTTP Keep-Alives are enabled by default in IIS 6.0, which complies with the HTTP/1.1 specification for HTTP Keep-Alives. IIS holds open an inactive connection for as long as the ConnectionTimeout metabase property specifies (the default value is 120 seconds).

If you disable HTTP Keep-Alives, the server ignores a clients request to keep the connection open. Therefore, disable HTTP Keep-Alives only for a specific reason and if you clearly understand how this change affects your server.

HTTP Keep-Alives are required for integrated security or connection-based authentication services, such as Integrated Windows authentication. If you disable HTTP Keep-Alives for Web sites that use Integrated Windows authentication, requests to the Web site fail.

How to Enable HTTP Keep-Alive on IIS 6.0

To enable HTTP Keep-Alives
1. In IIS Manager, expand the local computer, expand the Web Sites folder, right-click the Web site, and click Properties.

2. On the Web Site tab, in the Connections section, click the Enable HTTP Keep-Alives check box.

3. Click Apply, and then click OK.