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Testing forward and reverse DNS

posted Dec 19, 2008, 3:50 PM by Philip Rinehart   [ updated Dec 19, 2008, 3:51 PM by Greg Neagle ]
Written by Philip Rinehart   
Tuesday, 17 April 2007
Testing forward and reverse DNS is one of the common troubleshooting steps with Directory Services.

Often, nslookup or dig is the tool of choice to test the forward and reverse DNS lookup functionality.  As a quick review, forward DNS is the translation of and a given hostname to it's corresponding IP address, while reverse DNS is the translation of an IP address to its corresponding hostname.  Rather than using nslookup, the host command can be used instead, which is much faster and simpler.  Here' how:

 To test forward DNS

host hostname

Generally, the return value should be:

hostname has address 1.2.3.4

Testing reverse DNS follows the same form:

host 1.2.3.4

The return value should be similar to the following:

4.3.2.1.in-addr.arpa domain name pointer hostname 

 Notice the reverse IP address in the return value.  If both of these commands return information, forward and reverse DNS is working.

Last Updated ( Thursday, 03 January 2008 )
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