Windows Internet Name Service (WINS)

Windows Internet Name Service (WINS)

For clients who use the latest technology of Windows system, their PCs communicate with other Host on an Internet Protocol (IP) by using Domain Name System (DNS). However, clients that use older versions of Windows, such as Windows 95, 98, ME, NT 4.0, use network basic I/O system (NetBIOS) names for network communication.

So, in order for these PCs communicate properly nowadays, all these NetBIOS need to resolve into IP address. The Hosts(Servers) must have WINS installed to resolve NetBIOS to IP address for PCs which are still running the old version of Windows system and Unix boxes running Samba.

WINS features
WINS Server:
A computer that processes name registration requests from WINS clients, registers the client's name and IP addresses, and responds to NetBIOS name queries that clients submit. The WINS server then returns the IP address of a queried name, if the name is listed in the server database.

WINS database:
the WINS database stores and replicate the NetBIOS name to IP address mappings for a network.

WINS Client:
Computers that are directly pointing to a WINS server to register their NetBIOS name and to communicate with other computers registered with same WINS server on that network.

WINS proxy agents:
A computer that monitors broadcast for name query and give responds for all those names which are not located on the local subnet. WINS server communicates with the proxy for resolving names and then it caches the names for a particular time period.


How does WINS works?
As soon as a WINS client obtains the IP configuration from the DHCP server (or on bootup if the WINS server’s IP address was statically assigned), the WINS client issues a NameRegistrationRequest message to the WINS server. Unlike standard NetBIOS behavior, this message isn’t a broadcast. It is a message sent only to the primary WINS server and includes the client’s computer name and IP address.

The WINS server checks to see whether the computer name is listed in its database. If it isn’t listed, the WINS server assumes that it’s unique on the network and responds with a positive WINS name registration response.

The registration response includes a period called the time-to-live (TTL) during which the registration is valid. If the name isn’t unique, a negative response is sent to the client, and the WINS server sends a challenge to the name’s current owner. Typically, the computer that currently owns the name acknowledges that it is alive on the network and the negative response message informs the new computer that there is a conflict.