DOCUMENT:Q182644 10-AUG-2001 [crossnet] TITLE :DNR Sorts IP Address for Multihomed Hosts Before Returning List PRODUCT :Windows for Workgroups and Windows NT Networking Issues PROD/VER:WINDOWS:95; winnt:4.0 OPER/SYS: KEYWORDS:kbWinNT400sp4fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 4.0 - Microsoft Windows NT Server version 4.0 - Microsoft Windows 95 - Microsoft Windows NT Server version 4.0, Terminal Server Edition ------------------------------------------------------------------------------- SYMPTOMS ======== 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. CAUSE ===== 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. RESOLUTION ========== Windows NT 4.0 -------------- To 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: Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack Windows 95 ---------- This 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: Q182108 Availability of Windows Sockets 2.0 for Windows 95 STATUS ====== Windows NT 4.0 -------------- Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT Server 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. Additional query words: multi-homed multi homed ====================================================================== Keywords : kbWinNT400sp4fix Technology : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch kbWin95search kbZNotKeyword3 Version : WINDOWS:95; winnt:4.0 Issue type : kbbug Solution Type : kbfix ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.