Understanding NetBIOS Resource Record Flags

ID: Q189101

The information in this article applies to:

Microsoft Windows NT Server versions 3.5, 3.51, 4.0
Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0
Microsoft Windows versions 3.11, 95, 98

SUMMARY

The NetBIOS resource record flag fields define whether the record is unique or group and the second flag reports node type.

MORE INFORMATION

Text from section 4.2.1.3 of RFC 1002:


   NB_FLAGS field of the RESOURCE RECORD RDATA field for RR_TYPE of "NB":

                                             1   1   1   1   1   1
     0   1   2   3   4   5   6   7   8   9   0   1   2   3   4   5
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
   | G |  ONT  |                RESERVED                           |
   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

   Symbol     Bit(s)   Description:

   RESERVED     3-15   Reserved for future use.  Must be zero (0).
   ONT           1,2   Owner Node Type:
                          00 = B node
                          01 = P node
                          10 = M node
                          11 = Reserved for future use
                       For registration requests this is the
                       claimant's type.
                       For responses this is the actual owner's
                       type.
   G               0   Group Name Flag.
                       If one (1) then the RR_NAME is a GROUP
                       NetBIOS name.
                       If zero (0) then the RR_NAME is a UNIQUE
                       NetBIOS name.

The Owner Node Type (ONT) indicates the node type of the client. B node is 00, P node is 01, M node is 10, H node is 11.

The Group (G) is only used if the record is being registered/refreshed or released by the NetBIOS name server. If the flag is set to one, this indicates that the record is group NetBIOS name. If it is set to zero, it is a unique name.

The NetBIOS Name Server (NBNS) support of these fields is optional and Windows Internet Name Service (WINS), which is an NBNS server does not record the ONT field, nor do our clients use this field. Because of this, any WINS query response packet will populate this field with 00.

For more information about NetBIOS Resource Record Flags, please see RFC1002.

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Additional query words: Netbt flags netbios node

Keywords :
Version : Windows:3.11,95,98;WinNT:3.5,3.51,4.0
Platform : WINDOWS winnt
Issue type : kbinfo