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Posted to users@tomcat.apache.org by David Wall <dw...@myEastside.com> on 2001/07/06 06:02:29 UTC

Re: Reverse DNS lookup

> InetAddress.getByName(<ip address>).getHostName() will do what you
> want, if the info is available.

Where would the info have to be available?  Is there anything comparable to
a "dig -x" command under Unix?  For most IP addresses, there will not be
anything configured on my computer, but I know that ARPA reverse lookups are
possible.

The method you show above still returns the IP address on my system, yet a
"dig -x" will show the host name resolved.

David

Re[2]: Reverse DNS lookup

Posted by wi...@mailops.com.

Friday, July 06, 2001, 12:02:29 AM, dwall@myEastside.com wrote:

>> InetAddress.getByName(<ip address>).getHostName() will do what you
>> want, if the info is available.

DW> Where would the info have to be available?

in a PTR record on a nameserver

DW>  Is there anything comparable to
DW> a "dig -x" command under Unix?

dig just uses the PTR record

DW> For most IP addresses, there will not be
DW> anything configured on my computer, but I know that ARPA reverse lookups are
DW> possible.

DW> The method you show above still returns the IP address on my system, yet a
DW> "dig -x" will show the host name resolved.

maybe the dig command is using a cached value? In other words, if it
did a forward lookup on the hostname, then it might be returning
that name for the IP, even if no pointer record (in-addr-arpa) exists.

What is the IP that you're looking up?

DW> David