Troubleshooting Domain Name System

Domain Name System (DNS) logging and debugging settings can help you resolve problems with your DNS server.

DNS operates much the same as other TCP/IP functions and applications. Like SMTP or FTP applications, DNS jobs run under the QSYSWRK subsystem and produce job logs under the user profile QTCP with information associated with the DNS job. If a DNS job ends, you can use the job logs to determine the cause. If the DNS server is not returning the expected responses, the job logs might contain information that can help with problem analysis.

The DNS configuration consists of several files with several different types of records in each file. Problems with the DNS server are generally the result of incorrect entries in the DNS configuration files. When a problem occurs, verify that the DNS configuration files contain the entries you expect.

Identifying jobs

If you look in the job log to verify DNS server function (using WRKACTJOB, for example), consider the following naming guidelines:

• If you are using BIND 4.9.3, the job name of the server will be QTOBDNS. For more information about debugging DNS 4.9.3, refer to Troubleshooting DNS servers.

• If you are running servers based on BIND 8, there will be a separate job for each server instance you are running. The job name is 5 fixed chars (QTOBD) followed by the instance name. For example, if you have two instances, INST1 and INST2, their job names will be QTOBDINST1 and QTOBDINST2.

• Logging Domain Name System server messages
  Domain Name System (DNS) provides numerous logging options that can be adjusted when you are trying to find the source of a problem. Logging provides flexibility by offering various severity levels, message categories, and output files so that you can fine-tune logging to help you find problems.

• Changing Domain Name System debug settings
  The Domain Name System (DNS) debug function can provide information that can help you determine and correct DNS server problems.

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