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I'm attempting to improve my understanding of the DNS system and am confused as to how manages to resolve all DNs associate with an IP addr.

After playing around with dig, i'm stuck.

Example on domain

using dig::

$ dig +short                                                                             

$ dig +short -x                                                                                     

$ dig +short 28.24/

$ dig +short -x                                                                             

$ dig +short

Presumably is an alias for (?). Now using DomainTools web interface i get the promise of 129 results.

How can i find these results using commandline tools?

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You're using some feature of OpenDNS which redirects nonexistent DNS lookups to their own servers rather than returning NXDOMAIN. You can turn that off. – Michael Hampton Oct 30 '12 at 16:03

DNS doesn't contain an automatic IP to hostname lookup mechanism. It does have PTR records, but these are configured manually and don't correspond with the A records in most cases. Sites like simply have a big database of all the forward mappings they've discovered and they query this when an IP is looked up. The results are not guaranteed to be complete or up to date.

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