Microsoft KB Archive/127144

= Windows NT WinSock Listen (Backlog) Parameter Limit =

Article ID: 127144

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q127144



The WinSock listen call backlog parameter under Windows NT version 3.5 and 3.51 accepts a maximum value of 100.

The maximum backlog parameter is 5 on Windows NT 4.0 Workstation, and 200 on Windows NT 4.0 Server.

WinSock server applications use the listen call to establish a socket for listening for incoming connections. This calls second parameter, backlog, is defined as the maximum length to which the queue of pending connections may grow.

The WinSock version 1.1 specification states the maximum value for the backlog parameter is 5. However, Windows NT version 3.5 accepts up to 100 for this value.

Services that handle a large number of socket connections may be written to use a larger backlog value to prevent client connection requests from being dropped. This can be useful when writing applications such as World Wide WEB (WWW) and gopher servers.

Additional query words: prodnt

Keywords: kbapi kbnetwork kbwinsock KB127144

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