Registration of Group Names

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In addition to registration of unique names, mentioned in the preceding description of NetBIOS, WINS allows registration of group names. WINS recognizes two types of groups: normal groups and special groups.

Normal Group Names

A normal group name has several key differences compared to a normal unique name. Most important, it does not actually have an address associated with it. It is assumed to be valid on any subnet. The same group can be registered at more than one WINS server. The whole group has a single time associated with it that indicates the last time a node on any subnet registered or refreshed the name. When it receives a name query for the group, WINS returns the limited broadcast address (255.255.255.255). The WINS client then issues a broadcast to its subnet to resolve the name.

As the group names replicate from one WINS server to another, the name is added to the database of servers that do not already have it. However, since there is no address to propagate with the name, the entry for the group is just a name, without an associated address. When a group name is not refreshed, it is released and eventually becomes a tombstone.

The released and tombstoned states, however, have a slightly different meaning for group names than for unique entries. The WINS server answers name queries for released and tombstone groups. Unique name registrations that clash generate a negative response. For group entries, you can think of released and tombstoned states as pseudo states (pseudo-released and pseudo-tombstoned). These two states change at the end of the extinction interval, a configured value that establishes how long entries linger in the released and tombstoned states. After that interval, the version ID is incremented; this change means that the state information is then replicated to other WINS servers.

Special Group Names

When a name registration is received for a special group, WINS stores the actual address, rather than the limited broadcast address. A time stamp, reflecting the last registration or refresh received for that entry, and an owner ID are stored with each address entry in the group. When the WINS server receives a name query for such a group, it returns the IP addresses that have not expired. These groups, like normal groups, are replicated from the WINS server where they first registered to replication partners of that server.

Static NetBIOS name mappings can be any of the types listed in Table 7.4.

Table 7.4 Static NetBIOS Name Mappings

Type Option

Description

Unique

A unique name that maps to a single IP address.

Group

Also referred to as a "Normal" Group. When adding an entry to Group by using the WINS snap-in, you must enter the computer name and IP address.
The IP addresses of individual members of Group are not stored in the WINS database. Because the member addresses are not stored, there is no limit to the number of members that can be added to a Group. Broadcast name packets are used to communicate with Group members.

Domain

A NetBIOS name–to–IP address mapping that has 0x1C as the 16th byte. A domain group stores up to 25 addresses for members. For registrations after the 25th address, WINS overwrites a replica address, or if none is present, it overwrites the oldest registration. Domain names are used to add a static entry for the computer, specified by name in a static mapping to a list of domain controllers used on the network.

Internet group

Internet groups are user-defined groups that allow you to access group resources, such as printers, for easy reference and browsing. The default 16th byte of an Internet group name is set to 0x20. An Internet group can store a maximum of 25 addresses for members.
When you add an Internet group three unique records are added: InternetGroupName<0x20> is used for file registration. InternetGroupName<0x0> is used for workgroup registration, and InternetGroupName<0x3> is used by messenger service. (The messenger service is used for pop-up messages on the screen. For example the printer messages that tell you that printing is complete.)
This is similar to the domain group. Internet group members can be added via dynamic group registrations. A dynamic member, however, does not replace a static member added by using the WINS management console or importing the LMHOSTS file.

Multihomed

A unique name that can have more than one address, used for multihomed computers. No more than 25 addresses can be registered as multihomed. For registrations after the 25th address, WINS overwrites a replica address, or if none is present, it overwrites the oldest registration.