Microsoft KB Archive/173161

= How WINS Lookup Works from Windows NT DNS =

Article ID: 173161

Article Last Modified on 2/26/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q173161





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:


 * 1) A client sends a fully-qualified domain name (FQDN) query to the DNS Server.
 * 2) 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: 160828

TITLE : Network Monitor Parses DNS WINS Lookup queries as DNS Packets
 * 1) 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.
 * 2) 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: 154553

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:

 Type the following at a command prompt, and then press Enter:

net stop dns 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.  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.  Save the file and exit the editor. Type the following at a command prompt, and then press Enter:

net start d</li></ol>

-or-</li> Enable the Settings Only Affect Local Server option using the following steps:

<ol> Click Start, point to Programs, point to Administrative Tools, and then click DNS Manager.</li> Double-click your DNS Server, right-click the zone name that contains the WINS record, and then click Properties.</li> In the Zone Properties dialog, click on the WINS Lookup tab and click the Settings Only Affect Local Server option to enable it.</li></ol> </li></ul>

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:

<pre class="fixed_text">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:

<pre class="fixed_text">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:

<pre class="fixed_text">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:

<pre class="fixed_text">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

Keywords: kbinfo kbnetwork KB173161

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