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DNR Now Sorts IP Addresses for a Multihomed Host Before Returning the List to Winsock Applications
Article ID: 182644 - View products that this article applies to.
This article was previously published under Q182644
When a Windows sockets client application connects to a server application on a multihomed server, it may not connect to the "nearest" or "best" IP address on that server.
When a Windows sockets application is used to connect to another computer, it normally calls gethostbyname() to obtain the IP address of the target computer. This Winsock API invokes the Domain Name Resolver (DNR) component on the client computer to send a name query to a Domain Name Service (DNS) server. DNS returns a list of IP addresses to the DNR, which places the list into a structure and returns it to the application. Most applications then try to connect to the first IP address in the list.
An updated version of the DNR is now available. This version of the DNR sorts the list of IP addresses into the "best" order by examining the route table of the computer on which it is running. For instance, If any of the IP addresses in the list returned by the DNR are on a common subnet with the client, that IP address will be moved to the top of the list. This enhancement allows the client application to make the most direct connection possible to the server.
Windows NT 4.0To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/152734/EN-US/ )How to Obtain the Latest Windows NT 4.0 Service Pack
Windows 95This issue is resolved by the following updated files for Windows 95 with the Winsock2 update for Windows 95 installed:
Mswsock.dll version 4.10.1657 dated 4/8/98 4:57pm 71,168 bytes Rnr20.dll version 4.10.1657 dated 4/8/98 4:57pm 43,520 bytes
NOTE: The Windows Sockets 2.0 (Winsock2) update for Windows 95 must be installed on Windows 95 prior to installing this update. For additional information, please see the following article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/182108/EN-US/ )Availability of Windows Sockets 2.0 for Windows 95
Windows NT 4.0Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NTServer 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
Article ID: 182644 - Last Review: November 1, 2006 - Revision: 3.3