B.2 Special Handling of NetBIOS Names in WINS

B.2 Special Handling of NetBIOS Names in WINS

The Windows Internet Name Service (WINS) is Microsoft's implementation of the NetBIOS Name Server (NBNS) described in the RFCs. WINS does not match the RFC specifications, however, and its behavior is somewhat quirky. Known quirks are listed below.

Unique names

Unique names are handled per the RFC specifications with two exceptions: multi- homed host names and the Domain Master Browser name. Read on...

Multi-homed host names

Multi-homed hosts register unique names by sending a special MULTI-HOMED NAME REGISTRATION REQUEST packet to the NBNS. The procedure is described in Section 4.3.1.4 on page 81 of this book. WINS servers (and WINS-compatible NBNS implementations ) keep track of the list of IP addresses registered by a multi-homed host, and will report up to 25 IP addresses when queried for the multi-homed host name.

Group names

By default, in reply to a NAME QUERY REQUEST for a group name, WINS will send the limited broadcast address, 255.255.255.255. This is clearly not what the RFC authors had in mind.

Internet Group, Special Group, and Domain Group names

There are a few things to be said about these:

Thing 1

The terms "Internet Group" and "Special Group" are used interchangeably in much of the available documentation.

Thing 2

Older references use the terms "Internet Group" and "Special Group" when referring to group names with the <1C> suffix. More recent sources add the term "Domain Group" specifically for the nt_domain <1C> names, and expand the use of the other terms to include groups defined by adding a special static entry, with a suffix value of <20> , to the WINS database. ^[3]

^[3] It was difficult to find more than superficial documentation regarding the <20> Internet Group names, which suggests that the feature is not widely used. If you want to dig deeper, search the web for information regarding the #SG and #DOM keywords used in the LMHOSTS file.

Thing 3

Internet (aka Special) and Domain Groups are defined by using the #SG and #DOM keywords in the LMHOSTS file, or via WINS configuration dialogs on Windows systems.

As with multi-homed host entries, the WINS server should keep track of as many IP addresses per name as it can handle. When queried, the POSITIVE NAME QUERY RESPONSE should list at most 25 IP addresses per Internet Group name.

Local Master Browser

The LMB registers the workgroup <1D> unique name. A WINS server will accept all such registrations, ignoring any conflicts, and will reply with a NEGATIVE NAME QUERY RESPONSE when queried for the name. This behavior forces M and H nodes to search for the LMB on the local IP subnet. If there is no LMB for the Workgroup on the local subnet, then the client that sent the request may call for a browser election. P nodes cannot talk to Local Master Browsers, so they communicate directly with the Domain Master Browser (if there is one).

Domain Master Browser

The DMB registers the unique nt_domain <1B> name. The WINS server will ensure that the IP address associated with the nt_domain <1B> name is always the first in the list of IPs associated with the nt_domain <1C> Domain Group name.