How to change the default keep-alive time-out value in Internet Explorer

SUMMARY

This article describes how to change the default HTTP keep-alive value in Microsoft Internet Explorer.

When Internet Explorer establishes a persistent HTTP connection with a Web server (by using Connection: Keep-Alive headers), Internet Explorer reuses the same TCP/IP socket that was used to receive the initial request until the socket is idle for one minute. After the connection is idle for one minute, Internet Explorer resets the connection. A new TCP/IP socket is used to receive additional requests. You may want to change the HTTP KeepAliveTimeout value in Internet Explorer.

If either the client browser (Internet Explorer) or the Web server has a lower KeepAlive value, it is the limiting factor. For example, if the client has a two-minute timeout, and the Web server has a one-minute timeout, the maximum timeout is one minute. Either the client or the server can be the limiting factor.

By default, Internet Explorer has a

KeepAliveTimeout

value of one minute and an additional limiting factor (

ServerInfoTimeout

) of two minutes. Either setting can cause Internet Explorer to reset the socket.

MORE INFORMATION

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows

You may have to increase the default time-out value for persistent HTTP connections in Internet Explorer if you are using a Web program that must communicate with Internet Explorer over the same TCP/IP socket after one idle minute. To change the default time-out value for persistent HTTP connections in Internet Explorer, add a DWORD value that is named

KeepAliveTimeout

to the following registry key, and then set its value data to the time (in milliseconds) that you want Internet Explorer to wait before resetting an idle connection:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\InternetSettings

To do this, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following key in the registry:
   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\InternetSettings
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type KeepAliveTimeout, and then press ENTER.
5. On the Edit menu, click Modify.
6. Type the appropriate time-out value (in milliseconds), and then click OK. For example, to set the time-out value to two minutes, type 120000.
7. Restart Internet Explorer.

If you set the

KeepAliveTimeout

value to less than 60,000 (one minute), you may have problems communicating with Web servers that require persistent HTTP connections. For example, you may receive a "Page cannot be displayed" error message.

If you must have a

KeepAliveTimeout

value higher than 120000 (two minutes), you must create an additional registry key and set its value equal to the

KeepAliveTimeout

value that you want. The additional registry key is

ServerInfoTimeout

. It is a DWORD with a value (in milliseconds) and in the same location as

KeepAliveTimeout

.

For example, to use a three-minute

KeepAliveTimeout

value, you must create the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\InternetSettings

KeepAliveTimeout DWORD value 180000 (in milliseconds)
ServerInfoTimeout DWORD value 180000 (in milliseconds)

By default, HTTP 1.1 is enabled in Internet Explorer except when you establish an HTTP connection through a proxy server. When HTTP 1.1 is enabled, HTTP connections remain open (or persistent) by default until the connection is idle for one minute or until the value that is specified by the

KeepAliveTimeout

value in the registry is reached. You can modify HTTP 1.1 settings in Internet Explorer by using the Advanced tab in the Internet Options dialog box.