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Increasing Connection Limits with InternetSetOption() Does Not Affect Visited Servers

Article ID: 320721 - View products that this article applies to.

This article was previously published under Q320721

SYMPTOMS

Wininet.dll limits connections to a single HTTP 1.0 server to four simultaneous connections. Connections to a single HTTP 1.1 server are limited to two simultaneous connections. The HTTP 1.1 specification (RFC 2068) mandates the two-connection limit. The four-connection limit for HTTP 1.0 servers is a self-imposed restriction that coincides with the standard that is used by several popular Web browsers.

In Internet Explorer 5 and later, you can change the connection limit programmatically by calling the InternetSetOption function on a null handle with the following flags (note that this changes the connection limit for the whole process):

INTERNET_OPTION_MAX_CONNS_PER_SERVER
INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER

However, if a process has established a connection to a server, and you then change the connection limit by calling InternetSetOption, the change does not have any effect on additional connections on the same server. This behavior occurs even if you disconnect the previous connection before you call InternetSetOption.

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RESOLUTION

Internet Explorer 6

To resolve this problem, obtain the latest service pack for Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

322389

(http://support.microsoft.com/kb/322389/EN-US/ )

How to Obtain the Latest Windows XP Service Pack

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

(http://support.microsoft.com/contactus/?ws=support)

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The English version of this fix for IE 6.0 should have the following file attributes or later:

   Date         Time    Version        Size      File name
   ---------------------------------------------------------
   1-May-2002   20:02   6.0.2717.100   582,656   Wininet.dll

Internet Explorer 5.5 Service Pack 2

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Internet Explorer 5.5 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

(http://support.microsoft.com/contactus/?ws=support)

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix for Internet Explorer 5.5 SP2 should have the following file attributes or later:

   Date         Time    Version         Size      File name
   ----------------------------------------------------------
   1-May-2002   19:52   5.50.4917.100   481,040   Wininet.dll

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STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows XP Service Pack 1.

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MORE INFORMATION

Note that this hotfix corrects a previous limitation. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

183110

(http://support.microsoft.com/kb/183110/EN-US/ )

INFO: WinInet Limits Connections Per Server

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