WINS is the abbreviation of Windows Internet Name Server (Windows Internet Name Service). WINS provides name registration, update, release and conversion services for NetBIOS names. These services allow WINS servers to maintain a dynamic database that links NetBIOS names to IP addresses, greatly reducing the burden on network traffic.
1. Why do we need WINS services
In the default state, the NetBIOS name of each computer on the network is updated through broadcasting, that is, if there are n computers on the network, each computer will have to broadcast n-1 times. For small networks, this does not seem to affect network traffic, but when large networks, it increases the burden on the network. Therefore, WINS is particularly important for large and medium-sized enterprises.
2.WINS working principle
As mentioned above, the WINS server provides clients with name registration, update, release and conversion services. The following is a detailed introduction to the working principles of these four basic services:
1. Name registration
Name registration is the process by which the client obtains information from the WINS server. In WINS service, name registration is dynamic.
When a client starts, it sends a name registration information to the configured WINS server (including the client's IP address and computer name). If the WINS server is running and no other client computer has registered the same name, the server returns a successful registration message to the client computer (including the survival period of name registration-----TTL).
Like IP addresses, each computer requires a unique computer name, otherwise it will not be able to communicate. If the name has been registered by another computer, the WINS service will verify that the name is in use. If the name is in use, registration fails (send back a negative confirmation message), otherwise you can continue to register.
2. Name update
Because the client is assigned a TTL (survival period), all its registrations also have a certain period. After this period, the WINS server will delete the registration information of this name from the database. Its process is like this:
(1).After 1/8 of the survival period, the client begins to constantly try to update its name registration. If no response is received, the WINS client repeatedly updates the concentration every 2 minutes until the survival period is halfway.
(2).When the survival period is halfway through, the WINS client will try to update its lease with the second selected WINS server, and its process is the same as the preferred WINS server.
(3). If the time has passed halfway and still fails, the client will return to its preferred WINS server.
In this process, whether with the preferred or second selected WINS server, once the name registration is successful, the name registration of the WINS client will be provided with a new TTL value.
3. Name release
During the normal shutdown of the client, the WINS client sends a request to the WINS server for a name release to release the IP address and NetBIOS name mapped in the WINS server database. After receiving the release request, the WINS server verifies whether the IP address and NetBIOS name are present in its database. If so, it can be released normally, otherwise an error will occur (the WINS server sends a negative response to the WINS client).
If the computer does not shut down normally, the WINS server will not know that its name has been released, and the name will not expire until the WINS name registration record expires.
4. Name analysis
When a client needs a WINS server to resolve the name in many network operations, for example, when using shared files from other computers on the network, in order to get the shared files, the user needs to specify two things: the system name and the shared name, and the system name needs to be converted into an IP address.
The name resolution process is as follows:
(1). When the client computer wants to convert a name, it first checks the local NetBIOS name buffer.
(2). If the name is not in the local NetBIOS name buffer, a name query will be sent to the preferred WINS server (sent every 15 seconds, three times in total). If the request fails, the same request will be sent to the second selected WINS.
(3). If all fail, name resolution can be converted through other channels (such as local broadcast, lmhosts files and hosts files, or DNS for name resolution.
3. Requirements of WINS server and client
Requirements for servers
(1). Provide at least one preferred WINS server and one second selected WINS server to provide fault tolerance.
(2). A WINS server can handle nearly 1500 name registrations and about 4500 name queries per minute. Therefore, we strongly recommend that you have a preferred and a second choice WINS server that can drive 10,000 clients.
(3). If the WINS server and the client are not on the same subnet, the performance of the router must be taken into account.
2. Client requirements
Almost all Microsoft clients that support network interconnection can be WINS clients. The following lists clients that can work with WINS:
*Windows NT Server 3.5x,4.0
*Windows NT Workstation 3.5x,4.0
*Windows 9x/me/2000
*Windows for Workgroups with TCP/IP-32
*Microsoft Network Client 3.0 for MS-DOS
*LAN Manager 2.2c for MS-DOS
DOS-based clients can also use WINS servers for name resolution, but you must add static entries to them in the WINS server.
Article entry: dnbm Editor: dnbm