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Troubleshooting DNS (Domain Name Services) with IRM

Added 8/23/2004 - Article ID: KI0052

The IRM uses DNS to communicate with the data server.  Setting up DNS correctly is essential to the function of the entire RDP system, including the communication  between the IRM and Data Server.  If the tests below do not work, it is critical to set up DNS correctly using the steps in "Data server installation".  Topics covered in this document:

• Test DNS with NSLOOKUP on IRM and Data Server
• Verify Primary DNS Server is an Internal Server in the same Subnet as the IRM
• Examine Data in DNS Forward Lookup Zone
• Examine Data in DNS Reverse Lookup Zone
• Using IPCONFIG /RegisterDNS
• DNS does not work in a "Single-Label" Domain

Test DNS with NSLOOKUP on IRM and Data Server

The following table must be completed, with correct data returned from NSLOOKUP.  To collect this data:

1. Start a Command prompt
2. From the IRM Bridge, type "NSLOOKUP" <Enter>. The display will indicate what DNS server the IRM Bridge is using, which is controlled by the setting of the "primary DNS Server" in the TCP/IP properties on the IRM Bridge. The DNS server assigned to the IRM must be an internal machine, usually the data server.  Verify that the IP address is in the same subnet as the IRM.  For example, if the IP address of the IRM is 10.0.0.2, then the DNS server must be 10.0.0.x, where "X" is 1-254.   
3. From NSLOOKUP, enter the data server name.   This should return the correct IP address for the DataServer, which must be in the same subnet as the IP address of the IRM and the DNS server.  For example, if the IRM is 10.0.0.2, the DataServer has to be 10.0.0.x, where "x" is 1-254.
4. From NSLOOKUP, type the data server IP address. This should return the correct name.  This test verifies that DNS reverse lookup is working
5. Repeat the process above from the data server.  

Verify Primary DNS Server is an Internal Server in the same Subnet as the IRM

The most common problem that causes DNS to not function is the use of an EXTERNAL DNS Server for the Primary DNS server on the TCP/IP properties of the IRM Bridge.  An external DNS server can only resolve external IP addresses, such as " Yahoo ", " Google '', etc).  An internal DNS server must be installed and configured.

For example, if your DNS server is the RDP data server, and has an IP address of 10.0.0.1, then the DNS server for the IRM must be 10.0.0.1, and the IP address of the IRM server must be 10.0.0.x, where "x" is from 1-254.  

Examine Data in DNS Forward Lookup Zone

The DNS forward lookup zone is designed to find IP addresses when given the computer name.  The IRM will not function correctly unless it is registered in both the forward and reverse lookup zones on the DNS server.  To verify if a given workstation has successfully auto-registered with the DNS Forward lookup zone proceed as follows:  NOTE:  Only Windows 2000, 2003, and XP workstations are designed to auto-register with DNS.  Win ME, 98, 95 are actually unsupported operating systems and will never appear on the DNS server.

1. Login to your DNS Server, which is usually the RDP Data server, as administrator
2. Select Start | Settings |-Control Panel | Administrative Tools | DNS
3. Expand the data server name and the "forward lookup zones" and the zone name.  A screen similar to the following should appear.  In this example there are two computers in the forward lookup zone, as follows:
   

   Computer name	IP Address
   2003IRM	192.168.43.179
   dataserver	192.168.43.181

Examine Data in DNS Reverse Lookup Zone

The DNS reverse lookup zone is designed to find computer name when given the IP address.  The IRM will not function correctly unless it is registered in both the forward and reverse lookup zones on the DNS server.  To verify that the IRM, or any workstation has successfully auto-registered with the DNS Reverse Forward lookup zone proceed as follows:  NOTE:  Only Windows 2000, 2003, and XP workstations are designed to auto-register with DNS.  Win ME, 98, 95 are actually unsupported operating systems and will never appear on the DNS server. 

1. Login to your DNS Server, which is usually the RDP Data server, as administrator
2. Select Start | Settings |-Control Panel | Administrative Tools | DNS
3. Expand the data server name and the "reverse lookup zones" and the zone name.  A screen similar to the following should appear.  In this example there are two computers in the reverse lookup zone, as follows:

Using IPCONFIG /RegisterDNS

If a given computer does not appear in the DNS forward or reverse lookup zone, try the following:

1. Logon to the machine that does not register with DNS as Administrator.  NOTE:  Only Windows 2000, 2003, and XP are designed to auto-register with the DNS server.  
2. Select | Start | Run | CMD.  From the Command Prompt, type the following:
   
   IPCONFIG /REGISTERDNS
   
   
3. The system should display, "Registration of the DNS resource records for all adapters of this computer has been initiated. Any errors will be reported in the Event Viewer in 15 minutes."  Check the DNS settings in a few minutes to see if the computer is now in the forward and reverse lookup zone.  If not, check for errors using the Event Viewer, as follows:

• Start | Settings | Control Panel | Administrative Tools | Event Viewer
• Expand the System Log and errors or messages with a source of "DNS"

Note:  If a given computer still will not register with DNS, please call Microsoft Support.  RDP support is not able to troubleshoot Microsoft DNS issues.

DNS does not work in a "Single-Label" Domain

If the IRM bridge computer, or any other computer, does not register with the DNS server, the cause may be a "single-label" domain.  See Microsoft Knowledge base article #  826743, which states,

 " Starting with Windows 2000 SP4, the default setting for dynamically registering DNS records changed.
   In Windows 2000 SP4 and later, Windows does not dynamically register DNS records in a single-label   domain."

A "single-label" domain is one with only one name, such as "NEW1".  A correct domain name would be "New1.Local".  The ".Local" is critical.  To determine your domain name:

1. Login to your domain controller, which is usually the RDP Data server, as administrator
2. Right click "My Computer", left click properties, and then click the " Network Identification " tab.  A screen similar to the following appears:

Incorrect Single-Label Domain Example	Correct Multi-Label Domain Example
This domain below is an INVALID "Single-Label" domain name (NEW1)".   Computers will not be able to register with the DNS server of this domain, which will prevent the IRM, and other RDP workstations from functioning.   Unfortunately there is no way to rename a domain.  The only solution to this problem is to "start over" and recreate a new domain.  See Microsoft Knowledge base article #:  826743,	The domain name below is a VALID "multi-label" domain name (RDP2000.Local).  Computers should be able to auto-register with the DNS server for this domain.

Note:  If a given computer still will not register with DNS, please call Microsoft Support.  RDP support is not able to troubleshoot Microsoft DNS issues

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