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WINS proxies

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta

WINS proxies

A WINS proxy is a WINS client computer configured to act on behalf of other host computers that cannot directly use WINS. WINS proxies help resolve NetBIOS name queries for computers located on routed TCP/IP networks.

By default, most computers not able to use WINS use broadcasts to resolve NetBIOS name queries and register their NetBIOS names on the network. You can configure a WINS proxy to listen on behalf of these computers and to query WINS for names not resolved by broadcast.

WINS proxies are only useful or necessary on networks that include NetBIOS broadcast-only (or b-node) clients. For most networks, WINS-enabled clients are common and WINS proxies are typically not needed.

WINS proxies are WINS-enabled computers that listen for b-node NetBIOS name service functions (name registration, name release, and name query) and can respond for those names that are remote and not used on the local network. Proxies communicate directly with a WINS server to retrieve the information necessary to respond to these local broadcasts.

WINS proxies are used in the following ways:

  • When a b-node client registers its name, the proxy checks the name against the WINS server database. If the name exists in the WINS database, the proxy might send a negative registration response back to the b-node client attempting to register the name.

  • When a b-node client releases its name, the proxy deletes the client name from its remote name cache.

  • When a b-node client sends a name query, the proxy attempts to resolve the name using information either locally contained in its cache of remote names or through the use of information it obtains from the WINS server.

How WINS proxies resolve names

The following graphic illustrates the use of a WINS proxy, HOST-B, for a subnet containing a b-node client, HOST-A.

Example of WINS proxy

In this example, the following steps are used by the WINS proxy to resolve names for the b-node computer:

  1. HOST-A broadcasts a NetBIOS name query to the local subnet.

  2. HOST-B accepts the broadcast and checks its cache for the appropriate NetBIOS computer name-to-IP address mapping.

  3. HOST-B processes the request.

    If HOST-B has a name-to-IP address mapping cached that matches the one HOST-A requested, it returns this information to HOST-A. If not, HOST-B queries a WINS server for the mapping requested by HOST-A.

  4. When HOST-B receives the requested name-to-IP address mapping from its configured WINS server (in this example, WINS-A), it briefly caches this information.

    By default, a WINS proxy caches the remote name mappings that it queries in WINS for 6 minutes, but this value is configurable with a minimum value of 1 minute.

  5. HOST-B can then use this mapping information to respond to subsequent NetBIOS name queries broadcast from either HOST-A or other b-node computers on the subnet.

Notes

  • Because WINS servers do not respond to broadcasts, you should configure a computer as a WINS proxy on each subnet that contains non-WINS computers that must use broadcasts to resolve NetBIOS names.

  • When a WINS proxy is used to answer a query for a multihomed client or a group record containing a list of IP addresses, only the first listed address is returned to the b-node client.

  • For more in-depth information on configuring or using WINS proxy, see Updated technical information or "Windows Internet Name Service" at the Microsoft Windows Resource Kits Web site.