The Microsoft Windows Internet Name Service (WINS) Is an Enhanced Netbios Name Server (NBNS)

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APPENDIX B

WINS

The Microsoft® Windows® Internet Name Service (WINS) is an enhanced NetBIOS Name Server (NBNS) designed by Microsoft to eliminate broadcast traffic associated with the B-node implementation of NetBIOS over Transmission Control Protocol/Internet Protocol (TCP/IP). It is used to register NetBIOS computer names and resolve them to Internet Protocol (IP) addresses for both local and remote hosts.

Before two NetBIOS-based hosts can communicate, the destination NetBIOS name must be resolved to an IP address. This is necessary because TCP/IP requires an IP address to communicate. It cannot establish communication using a NetBIOS computer name. The procedure is as follows:

1.In a WINS environment, each time a WINS client starts, it registers its NetBIOS name/IP address mapping with a configured WINS server.

2.When a WINS client initiates a Microsoft WindowsNT® command to communicate with another host, the name query request is sent directly to the WINS server instead of broadcasting it on the local network.

3.If the WINS server finds a NetBIOS name/IP address mapping for the destination host in this database, it returns the destination host’s IP address to the WINS client. Because the WINS database obtains NetBIOS name/IP address mappings dynamically, it is always current.

Why Use WINS?

WINS provides the following advantages:

uClient requests for name resolution are sent directly to a WINS server. If the WINS server can resolve the name, it sends the IP address directly to the client. As a result, a broadcast is not needed, and network traffic is reduced. However, if the WINS server is unavailable, the WINS client can still use a broadcast in an attempt to resolve the name.

uThe WINS database is updated dynamically, so it is always current. This eliminates the need for an LMHOSTS file.

uWINS provides internetwork and interdomain browsing capabilities.

How WINS Works

The process WINS uses to resolve and maintain NetBIOS names is similar to the B-node implementation.

The method used to renew a name is unique to NetBIOS node types that use a NetBIOS Name Server.

WINS is an extension of Request for Comment (RFC) 1001 and RFC 1002. WINS uses standard methods of name registration, name discovery, and name release. The method used to renew a name is unique to NetBIOS node types that use a NetBIOS name server.

Name Registration

Each WINS client is configured with the IP address of a primary WINS server and optionally, a secondary WINS server. When a client starts, it registers its NetBIOS name and IP address with the configured WINS server. The WINS server stores the client’s NetBIOS name/IP address mapping in its database.

Name Renewal

All NetBIOS names are registered on a temporary basis so the same name can be used later by a different host if the original owner stops using it.

Name Release

Each WINS client is responsible for maintaining the lease on its registered name. When the name will no longer be used, such as when the computer is shut down, the WINS client sends a message to the WINS server to release it.

Name Query and Name Resolution

After a WINS client has registered its NetBIOS name and IP address with a WINS server, it can communicate with other hosts by obtaining the IP address of other NetBIOS-based computers from a WINS server.

All WINS communications are done using directed datagrams over UDP port 137 (NetBIOS Name Service).

WINS Requirements

To implement WINS, both the server and client require configuration.

WINS Server

A WINS server requires the following:

uThe WINS Server service must be configured on at least one computer running WindowsNT Server within the TCP/IP internetwork. (This server does not need to be a domain controller.)

uA static IP address.

WINS Client

A WINS client must be running one of the following operating systems:

uWindowsNT Server 3.5 or later.

uWindows NT Workstation 3.5 or later.

uWindows95.

uWindows for Workgroups 3.11 running Microsoft TCP/IP-32.

uMicrosoft Network Client 3.0 for MS-DOS with the real-mode TCP/IP driver from the Microsoft WindowsNT Server compact disc.

uLAN Manager 2.2c for MS-DOS (included on the Microsoft WindowsNT Server compact disc). LAN Manager 2.2c for OS/2 is not supported.

The WINS client also requires the IP address of a WINS server.