Deletion of WINS Database Records
The WINS management console provides improved database management by supporting the following deletion operations:
Simple deletion of WINS database records stored on a single-server database.
Tombstoned deletion of WINS database records replicated to databases on other WINS servers.
The ability to select multiple groups of displayed database records when performing either simple or tombstoned deletion.
In addition, the WINS management console allows you a simpler and more convenient tool for administratively removing dynamically registered records. In previous releases of WINS, the WINS management console utilities only removed static mappings.
WINS records can be removed in one of two ways: either through simple deletion or by using tombstoned deletion. The rest of this section discusses how to use both to manage your WINS database.
When simple deletion is used, records selected using the WINS console are removed from the current local WINS server that you are managing.
If WINS records deleted this way have been replicated to other WINS servers, these additional records will not be removed fully. The records on other WINS servers remain in those databases unless you specifically use the WINS console to remove them from each server, one at a time. In addition, records deleted on just one server might reappear when replication next occurs between WINS servers configured as replication partners.
When you use tombstoned deletion to remove a record owned by your selected server, the selected records are removed from all WINS servers that replicate the records as described in this section.
The owning WINS server changes the status of selected WINS records from active to tombstoned in its database. WINS then treats the records as inactive and released from use. Once these records are tombstoned locally, the owning WINS server neither responds to nor resolves NetBIOS name queries for these names from other WINS clients and WINS servers unless the records are registered again by the WINS client. The owning WINS server replicates the selected records as "tombstoned" to other WINS servers during subsequent replication cycles.
The records are not forcibly and immediately removed from WINS; instead, they are flagged for eventual deletion. The exact replication cycle interval is configured based on the Name Record properties of the server set in the WINS console. Records are not removed from WINS databases until their extinction interval has actually expired. This allows other WINS servers to learn that these records are no longer in use, update their replicated record mappings, and further replicate this updated WINS data to other servers. The records are marked extinct on all replicated WINS servers.
Once all WINS servers have completed a full replication cycle, the tombstoned records expire and are removed from the database on each WINS server during the next database scavenging operation. Once scavenging occurs on all servers, the records no longer appear in the WINS management console and are no longer physically stored in the WINS database.
Note that even if records are manually tombstoned (or otherwise marked as released by WINS), released records remain in the WINS database briefly before being removed during subsequent scavenging operations. Exactly how long they remain depends on the length of time required by the WINS server to determine extinction. Typically, the time to extinction for records is equal to the sum of the extinction interval, the extinction timeout, and the verification interval.
Example of Record Registration and Extinction
As an example, a WINS client registers the name TESTPC1 with the WINS server WINS1, and the server provides a refresh interval of three days. Once the name is registered, WINS1 replicates this record to its replication partners, such as WINS server WINS2. When the verification interval has expired, WINS2 verifies the record with WINS1. WINS1 takes no further action with this record; it simply waits until the client refreshes its name or reregisters it.
If the client does not refresh its name within the refresh interval, WINS1 sets the state for the name TESTPC1 to "released." If the client does not refresh the name within the extinction interval, the name is tombstoned; at that point, it is again replicated to WINS2 (because the version ID of the record for TESTPC1 is increased).
When the record is replicated, WINS2 copies the tombstoned entry from WINS1 and stamps it with the current time plus the verification interval. WINS2 does not query WINS1 until after the verification interval elapses. On the other hand, WINS1 waits for the duration of the extinction interval for the client to refresh or reregister its name. If the client does not do so, WINS1 removes the name from the database. WINS2 then queries WINS1 when the verification interval expires; if the record is not present at WINS1, then WINS2 removes the record from its database.
If WINS2 queries WINS1, and WINS1 does not respond (due to failure, maintenance, or simply a slow link), then the record is not removed. In this case, the entry's verification interval is reset, and WINS2 queries WINS1 after the verification interval has again expired.
With earlier versions of WINS, records were not deleted on multiple servers simultaneously. A window existed during which replication could occur between servers whose records were inconsistent. In other words, deleted records could return to a server from which they were just deleted.
The manual tombstoning option of Windows 2000 WINS prevents this problem. The length of the tombstoned state is greater than the propagation delay incurred with replication across the network. When the time limit is reached, tombstoned records are deleted by normal scavenging.
Manual tombstoning provides an excellent way of dealing with static records, too.
When the tombstoned records are replicated, the tombstone status is updated and applied by other WINS servers that store replicated copies of these records. Each replicating WINS server updates and individually tombstones these records. Once all WINS servers have replicated these records, the records are automatically removed from WINS after the period set by the verification interval of each server.
Manual tombstoning is available from both the WINS graphical user interface and the WINS command-line interface. To access this feature, open the WINS dialog box, select the owning server, then view all the records of that server. Highlight the record you want to delete, and delete it from the Action menu. At this point, you can either delete or tombstone the record. While the ability to manually tombstone records requires Windows 2000 WINS servers, tombstoned records replicate normally to Windows NT 3.51 and Windows NT 4.0 servers.