DNS > Troubleshooting DNS

Most often, DNS configuration problems are exposed when one or more DNS client computers are unable to resolve host names.The first step in troubleshooting DNS problems is to determine the scope of the problem by using the ping command on multiple clients to resolve the names of hosts on the intranet and the Internet and to test overall network connectivity.

Use the following commands on several DNS client computers and with several different target computers, and note the results:

• ping internal_host_ip_address
• ping internal_host_name
• ping Internet_host_name

Where internal_host_ip_address is the Internet Protocol (IP) address of a computer that exists in the client's domain, internal_host_name is the DNS domain name of the computer, and Internet_host_name is the name of a computer that exists on the Internet.

Note
that it is not important whether an Internet computer responds to the ping request, only whether the specified name can be resolved to an IP address. The results of these tests will suggest the nature of the problem, as listed in the following information.

Multiple clients cannot resolve any intranet or Internet names
This might indicate that the clients cannot access the assigned DNS server. This might be the result of general network problems, particularly if ping using IP addresses fails. Otherwise, if the clients are configured to obtain DNS server addresses automatically, the DHCP servers on the network might not be configured properly.

Multiple clients cannot resolve intranet names, but can resolve Internet names
This suggests that host (A) resource records or other records (such as SRV records) do not exist in the DNS zone database. Check to ensure that the appropriate resource records exist and that the DNS server is properly configured to receive automatic updates, as appropriate. If the target host names are located in a particular child zone, ensure that delegation of that zone is properly configured.

Multiple clients cannot resolve Internet names, but can resolve intranet names
The designated forwarder of the DNS domain is unavailable, or the DNS server is not properly configured to use a forwarder.

One client only cannot resolve any intranet or Internet names
If the ping command using IP addresses fails, this indicates that the client computer cannot connect to the network at all. Ensure that the client computer is physically connected to the network and that the network adapter for the computer is functioning properly. If the ping command using IP addresses succeeds, but ping cannot resolve DNS domain names, then the TCP/IP settings of the client are probably incorrect.

One client only cannot resolve intranet names, only Internet names
If the client computer was previously configured to connect directly to the Internet, its TCP/IP properties might be configured to use an external DNS server, such as a DNS server from an Internet Service Provider (ISP).

In most cases, the client should not use a DNS server from an ISP as either the preferred or alternate DNS server, because the DNS server at the ISP is unable to resolve internal names. Using a DNS server from an ISP in the TCP/IP configuration of a client can also cause problems with conflicting internal and external namespaces.

If you have ruled out all of these potential problems for a particular client and still cannot resolve DNS names, use the following procedure to verify the DNS client settings.

To verify DNS client configuration in TCP/IP settings

1. Log on to the DNS client computer with the Administrator account.
2. Click Start, click Control Panel, and then double-click Network Connections.
3. In Network and Dial-up Connections, right-click the local area connection that you want, and then click Properties.
4. In Local Area Network Connection Properties, click Internet Protocol (TCP/IP), and then click Properties.
5. If Obtain an IP address automatically is selected, type the following at a command prompt, and then press
   ENTER: ipconfig /all
6. Review the DNS server settings and verify that they are correct.

If the client does not have a valid TCP/IP configuration, you can either:

• For dynamically configured clients, use the ipconfig /renew command to manually force the client to renew its IP address configuration with the DHCP server.
• For statically configured clients, modify the client TCP/IP properties to use valid configuration settings or complete its DNS configuration for the network.