Windows Internet Name Service part 2

Posted by arlene

Configuring WINS Clients

To use WINS, a client must first be configured with the address of a WINS server. This can be done in one of two ways. First, you could configure the client manually, using a network properties page for the particular Windows operating system. Second, you could configure a DHCP server to provide the name of one or more WINS servers to a client if you use DHCP in your. network.

If your network consists of nothing but Windows 2000, Windows XP, or Windows Server 2003 computers, you won’t need the WINS service. The Active Directory combined with DHCP and a dynamic DNS server provide all the name registration and resolution functionality you need. However, Windows 2000 clients can still be configured to use WINS. This might be necessary if you have a mixed network using clients from Windows 98, Windows NT, or even Unix or Linux clients that have Samba installed.

To configure a Windows 2000 client to use WINS, follow these steps:

  1. Click Start, Settings, Network and Dialup Connections.
  2. Right-click on the network connection you want to set up to use WINS and select Properties from the menu that appears.
  3. Click once on Internet Protocol (TCP/IP) and click the Properties button.
  4. Click the Advanced button at the bottom of the Properties page. The Advanced TCP/IP Settings Properties page is displayed. Click the WINS tab.
  5. Click the Add button. A dialog box pops up that you can use to enter the IP address of a WINS server. Enter the address and click OK. Continue using the Add button to add more WINS servers, if they’re present on your network for backup purposes.

Living the Web 2.0To remove a WINS server, simply highlight the server you want to remove by clicking on it once and then click the Remove button. The Edit button can be used to change an entry. Highlight the entry and click the Edit button, and the same dialog box used for adding WINS servers pops up. The WINS server you’ve selected to edit appears in the fields on this dialog box. You can change any part of the IP address and click OK.

One final note about Windows 2000 clients that network administrators will appreciate: You don’t have to perform a reboot of the computer after you add, edit, or remove WINS servers.

Client Name Registration and Release

For a client computer to register a name with the WINS server, it sends a name registration request to the server. This is a directed message, not a broadcast message—that’s why you have to configure the client to know the address of one or more WINS servers. If the name is not found in the database, the WINS server returns a positive name registration response to the client. The record is given a time- stamp, and a renewal interval is also recorded in the record. The record is given an owner ID as well, which identifies the WINS server that originated (or in other words, owns) the record. When the record is replicated to other WINS servers, they use this ID to identify the original server.

After half of the renewal period has elapsed, a Windows client attempts to reregister its ownership of the name by sending the server a name refresh request. The re-registration process functions the same as the initial registration. By setting a time-to-live (TTL) value on each record, the WINS database can eventually be purged of records that are no longer valid.

The state of the name record changes over time depending on the status of the client. At any time, a record is either in the active state or it can be marked as released or extinct. At each state, a TTL is marked on the record and is used to determine when to change it to the next state.

A name can be released in two ways:

When the name is released, the WINS server does not yet delete the record from the database. Instead, it marks the record as released, adds another timestamp (showing the time of the release), and then adds an extinction interval to the record. If the WINS server that receives the release is the original owner of the record, it does not propagate a record update to other WINS servers, which reduces replication traffic. If another WINS server that still has a record showing the name is active receives a request from another computer to use the name, it tries to contact the original owner and find out whether the name can be reused.

At certain intervals, the WINS server scavenges the database. If it finds a record whose extinction interval has expired, it marks the record as extinct. This state is often referred to as the tombstone state. When a record is marked as extinct, it receives another timestamp and an extinction time-out value. If a record has not been re-registered by the end of this final time-out interval, the scavenge process will finally remove it from the database.

If a WINS server receives an explicit release request from a client and the server is not the original owner of the record, it makes itself the new owner of the record. Instead of placing the record into the released state, it proceeds directly to the extinct state. Unlike records in the released state, records in the extinct state do get replicated at replication time. The reason that a WINS server immediately marks a record it does not own as extinct is so that the record will be replicated quickly and will get back to the WINS server that originated the record.

If a name is already in the database, the client can still be awarded ownership of it, depending on certain factors. If the name is in the released or extinct state, the server knows that it can reassign the name because the previous owner has released it. If the name is in the active state, the WINS server tries to contact the original owner. If the original owner does not respond, the WINS server reassigns the name to the node that’s requesting it.

When a client workstation is moved to a new subnet and receives a new address, it sends a name registration request to the WINS server. The WINS server queries the old IP address, determines that the name is no longer in use, and then grants the name to the new IP address.

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