Troubleshooting DNS Servers

Three main options exist for troubleshooting DNS servers that you should be aware of. The first is the monitoring tab on the properties of the DNS server.

This tool allows you to pass queries to the DNS server to ensure it is functioning correctly. A simple query is passed only to this server for resolution, and will either pass or fail. A recursive query is one in which a DNS server will attempt to query other DNS servers to obtain an answer, which will again be presented as a pass or fail. This tool can also be used to test DNS on a regular basis, as specified by the test interval.

DNS logging can also be used for troubleshooting purposes, as it will log when certain DNS events occur. Found on the Logging tab of a DNS server’s properties, all output is saved to a text file called dns.log located in the %systemroot%\system32\dns folder on the server. Note that excessive logging may have a negative impact on server performance, and as such should only be used for troubleshooting purposes.

More commonly, Nslookup is the tool used to query a DNS server. This command line utility allows you to search for resource records relating to a domain. Use the /? option for a list of supported commands.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.