Windows Internet Name Service
Windows Internet Name Service |
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When a WINS-enabled computer starts, it attempts to register its NetBIOS names and corresponding IP address directly with the WINS server. If the registration fails, the WINS client tries again every 10 minutes until it is successful. The message the client sends is referred to as a name registration request. The WINS client sends one name registration request (which includes the computer IP address) for each NetBIOS-based networking service running on the computer.
Note that the IP address is dynamically assigned by a DHCP server if the client is DHCP-enabled. If DHCP is not used, the IP address is a statically assigned number which you must get from a network administrator and manually configure on the computer.
To create a static mapping with WINS
Figure 7.2 shows the Create Static Mapping dialog box.
Figure 7.2 Static Mapping in WINS
When the WINS server receives a name registration request for a unique NetBIOS name, it checks whether the name already exists in its WINS database. The WINS server responds with either a positive or negative name registration response. Table 7.2 describes each type of WINS server name registration response.
Table 7.2 WINS Server Responses
| Server response | Explanation |
|---|---|
| No response | The WINS client sends another name registration request for the same name. |
| Positive | The WINS server does not find a duplicate name in the WINS database, and sends a positive response to the registering client. The response includes a Time-To-Live (TTL) value, which sets the time the server the name registration will be active in the database. The client must renew the registration before the TTL expires. |
| Negative | The WINS server finds an existing registration for the requested name in the database. The server sends a wait for acknowledgment (WACK) packet to the client and then sends a challenge, referred to the registered owner of the name. Having received a response from the registered owner, the server sends a negative name registration response to the WINS client attempting to register the name. |
When a WINS server receives a name registration request for a name already in its database, the server sends a challenge, known as a name query request, to the owner of the registered name. The server waits 500 milliseconds between challenges, and if the client is multihomed, the WINS server tries each IP address it has for the computer until the WINS server receives a response or until it has tried all of the IP addresses.
Figure 7.3 illustrates the flow of messages between client, server, and challenged client. The first message is the name registration request; the last is the name response.
Figure 7.3 WINS Client Name Registration
In the first step in Figure 7.3, the Corp01 computer sends a message to its WINS server to register its address using a NetBIOS name registration message. The server replies with an acknowledgment of the address with a NetBIOS name registration response. Note that there is a second WINS server on the far side of the router; this server learns about the Corp01 address when the WINS server database replicates itself.
