How WINS Lookup Works from Windows NT DNS

ID: Q173161

The information in this article applies to:

Microsoft Windows NT Server version 4.0
Microsoft Windows 2000 Server
Microsoft Windows 2000 Advanced Server

SUMMARY

The Microsoft Windows NT Server 4.0 Domain Name Service (DNS) Server has the ability to interact with a Windows Internet Name Service (WINS) Server. This article discusses this feature and the process that takes place when a DNS Server forwards a query to a WINS Server.

For additional information on DNS, please see the following whitepaper available on the Microsoft anonymous ftp server:

File : ftp://ftp.microsoft.com/bussys/winnt/winnt-docs/papers/Dnswp.exe
Title : "DNS and Microsoft Windows NT 4.0"

MORE INFORMATION

To allow for interoperability between DNS and WINS, two new resource records were defined as part of the Windows NT DNS implementation. The following are the two new records:

WINS Lookup

WINS-R Lookup (WINS Reverse Lookup)

WINS Lookup

The first new record is called a WINS Lookup record and can only be a part of the zone root domain. Any queries that cannot be resolved by the static entries in the DNS zone file will be forwarded to the WINS server(s) defined by the WINS Lookup record. This function is particularly useful for Unix clients that may need to contact DHCP/WINS enabled clients through IP.

The process that takes place is as follows:

A client sends a fully-qualified domain name (FQDN) query to the DNS Server.

The DNS Server, being unable to resolve the name locally, truncates the domain name from the host name and forwards the query to the configured WINS Server(s). The DNS Server uses a source port of UDP 53 (DNS) and a destination port of UDP 137 (NetBIOS Name Service). It also encrypts the name that it sends to the WINS Server.

For additional information, please see the following article(s) in the Microsoft Knowledge Base:

ARTICLE-ID: Q160828
TITLE : Network Monitor Parses DNS WINS Lookup queries as DNS Packets

The WINS Server responds to the DNS Server with the resolved IP address and a source port of UDP 137 and destination port UDP 53.

The DNS Server forwards the IP address in response to the client's original query.

NOTE: For network administrators who are familiar with protocol analyzers, a sample of packets has been included at the end of this article to display the actual network data that is exchanged in the above steps.

WINS-R Lookup

There is also a WINS-R or WINS Reverse Lookup entry that can be added to the reverse zone. Because WINS does not have a reverse lookup capability, however, this record instructs the DNS server to perform a NetBIOS node adapter status lookup, or an NS Query, against the host.

For additional information, please see the following article(s) in the Microsoft Knowledge Base:

ARTICLE-ID: Q154553
TITLE : Windows NT 4.0 DNS WINS Reverse Lookups Do Not Use WINS

NOTE: The WINS Lookup and the WINS-R Lookup resource records are proprietary to the Microsoft NT DNS Server. You will want to prevent the resource records from being propagated in a zone transfer to a non-Windows NT DNS Server. This can be accomplished by using one of the following methods:

Add the Local flag to the WINS record in the zone file using the following steps:
1. Type the following at a command prompt, and then press Enter:
  
  net stop dns
2. Using a text editor, open your zone file. For example, if your zone is Domain.com, then your default zone file name is Domain.com.dns.
3. Locate the WINS record, and insert LOCAL so that your WINS record looks similar to the following:
```
         @   0   IN   WINS   LOCAL   a.b.c.d 
```
  where a.b.c.d is the IP address of your WINS Server.
4. Save the file and exit the editor.
5. Type the following at a command prompt, and then press Enter:
  
  net start dns
-or-

Enable the Settings Only Affect Local Server option using the following steps:
1. Click Start, point to Programs, point to Administrative Tools, and then click DNS Manager.
2. Double-click your DNS Server, right-click the zone name that contains the WINS record, and then click Properties.
3. In the Zone Properties dialog, click on the WINS Lookup tab and click the Settings Only Affect Local Server option to enable it.

Network Monitor Trace Information

Network Monitor is a protocol analyzer that is available with Microsoft Systems Management Server (SMS). Corresponding to the four steps listed above there are four frames of data following to further illustrate the process involved when a Windows NT DNS Server forwards a query to a WINS Server.

Frame 1:


1  7.128 WIN95B  -->  DNS SERVER  DNS 0x1:Std Qry for thebunker.gotcha.com.
of type Host Addr on class INET addr. WIN95B  -->
157.54.51.20   IP

DNS: 0x1:Std Qry for thebunker.gotcha.com. of type Host Addr on class INET
addr.

    DNS: Query Identifier = 1 (0x1)
    DNS: DNS Flags = Query, OpCode - Std Qry, RD Bits Set, RCode - No error
        DNS: 0............... = Query
        DNS: .0000........... = Standard Query
        DNS: .....0.......... = Server not authority for domain
        DNS: ......0......... = Message complete
        DNS: .......1........ = Recursive query desired
        DNS: ........0....... = No recursive queries
        DNS: .........000.... = Reserved
        DNS: ............0000 = No error
    DNS: Question Entry Count = 1 (0x1)
    DNS: Answer Entry Count = 0 (0x0)
    DNS: Name Server Count = 0 (0x0)
    DNS: Additional Records Count = 0 (0x0)
    DNS: Question Section: thebunker.gotcha.com. of type Host Addr on class

INET addr.

        DNS: Question Name: thebunker.gotcha.com.
        DNS: Question Type = Host Address
        DNS: Question Class = Internet address class

Frame 2:


2    7.129 DNS SERVER -->  WINS SERVER DNS 0x8008:Std Qry for
FEEIEFECFFEOELEFFCCACACACACACAAA. of type Unknown Type on class INET
addr. 157.54.51.20 --> 157.54.51.30 IP

UDP: Src Port: DNS, (53); Dst Port: NETBIOS Name Service (137); Length = 58
(0x3A)
UDP: Source Port = DNS
UDP: Destination Port = NETBIOS Name Service
UDP: Total length = 58 (0x3A) bytes
UDP: UDP Checksum = 0x70AB
UDP: Data: Number of data bytes remaining = 50 (0x0032)
DNS: 0x8008:Std Qry for FEEIEFECFFEOELEFFCCACACACACACAAA. of type Unknown
Type on class INET addr.

    DNS: Query Identifier = 32776 (0x8008)
    DNS: DNS Flags = Query, OpCode - Std Qry, RD Bits Set, RCode - No error
        DNS: 0............... = Query
        DNS: .0000........... = Standard Query
        DNS: .....0.......... = Server not authority for domain
        DNS: ......0......... = Message complete
        DNS: .......1........ = Recursive query desired
        DNS: ........0....... = No recursive queries
        DNS: .........000.... = Reserved
        DNS: ............0000 = No error
    DNS: Question Entry Count = 1 (0x1)
    DNS: Answer Entry Count = 0 (0x0)
    DNS: Name Server Count = 0 (0x0)
    DNS: Additional Records Count = 0 (0x0)
    DNS: Question Section: FEEIEFECFFEOELEFFCCACACACACACAAA. of type

Unknown Type on class INET addr.

        DNS: Question Name: FEEIEFECFFEOELEFFCCACACACACACAAA.
        DNS: Question Type = 0x0020
        DNS: Question Class = Internet address class

Frame 3:


3    7.133 WINS SERVER -->  DNS SERVER DNS 0x8008:Std Qry Resp. for
FEEIEFECFFEOELEFFCCACACACACACAAA. of type Unknown Type on class
INET addr. 157.54.51.30 -->  157.54.51.20 IP

UDP: Src Port: NETBIOS Name Service, (137); Dst Port: DNS (53); Length = 70
(0x46)

    UDP: Source Port = NETBIOS Name Service
    UDP: Destination Port = DNS
    UDP: Total length = 70 (0x46) bytes
    UDP: UDP Checksum = 0xBBB7
    UDP: Data: Number of data bytes remaining = 62 (0x003E)

DNS: 0x8008:Std Qry Resp. for FEEIEFECFFEOELEFFCCACACACACACAAA. of type
Unknown Type on class INET addr.

    DNS: Query Identifier = 32776 (0x8008)
    DNS: DNS Flags = Response, OpCode - Std Qry, AA RD RA Bits Set, RCode -

No error

        DNS: 1............... = Response
        DNS: .0000........... = Standard Query
        DNS: .....1.......... = Server authority for domain
        DNS: ......0......... = Message complete
        DNS: .......1........ = Recursive query desired
        DNS: ........1....... = Recursive queries supported by server
        DNS: .........000.... = Reserved
        DNS: ............0000 = No error
    DNS: Question Entry Count = 0 (0x0)
    DNS: Answer Entry Count = 1 (0x1)
    DNS: Name Server Count = 0 (0x0)
    DNS: Additional Records Count = 0 (0x0)
    DNS: Answer section: FEEIEFECFFEOELEFFCCACACACACACAAA. of type Unknown

Type on class INET addr.

        DNS: Resource Name: FEEIEFECFFEOELEFFCCACACACACACAAA.
        DNS: Resource Type = 0x0020
        DNS: Resource Class = Internet address class
        DNS: Time To Live = 0 (0x0)
        DNS: Resource Data Length = 6 (0x6)
        DNS: Additional Resource Data = 60 00 9D 36 33 1E

Frame 4:


4   7.0134 WIN95B  -->  DNS SERVER  DNS 0x1:Std Qry Resp. for
thebunker.gotcha.com. of type Host Addr on class INET addr.
157.54.51.20 -->  WIN95B  IP

DNS: 0x1:Std Qry Resp. for thebunker.gotcha.com. of type Host Addr on class
INET addr.

    DNS: Query Identifier = 1 (0x1)
    DNS: DNS Flags = Response, OpCode - Std Qry, AA RD RA Bits Set, RCode -

No error

        DNS: 1............... = Response
        DNS: .0000........... = Standard Query
        DNS: .....1.......... = Server authority for domain
        DNS: ......0......... = Message complete
        DNS: .......1........ = Recursive query desired
        DNS: ........1....... = Recursive queries supported by server
        DNS: .........000.... = Reserved
        DNS: ............0000 = No error
    DNS: Question Entry Count = 1 (0x1)
    DNS: Answer Entry Count = 1 (0x1)
    DNS: Name Server Count = 0 (0x0)
    DNS: Additional Records Count = 0 (0x0)
    DNS: Question Section: thebunker.gotcha.com. of type Host Addr on class

INET addr.

        DNS: Question Name: thebunker.gotcha.com.
        DNS: Question Type = Host Address
        DNS: Question Class = Internet address class
    DNS: Answer section: thebunker.gotcha.com. of type Host Addr on class

INET addr.

        DNS: Resource Name: thebunker.gotcha.com.
        DNS: Resource Type = Host Address
        DNS: Resource Class = Internet address class
        DNS: Time To Live = 600 (0x258)
        DNS: Resource Data Length = 4 (0x4)
        DNS: IP address = 157.54.51.30

Additional query words:

Keywords : kbnetwork ntnetserv NTSrv
Version : WINDOWS:2000; winnt:4.0
Platform : WINDOWS winnt
Issue type : kbinfo