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From w...@mailops.com
Subject Re[2]: Reverse DNS lookup
Date Fri, 06 Jul 2001 12:25:59 GMT


Friday, July 06, 2001, 7:02:45 AM, randy.layman@aswethink.com wrote:


RL>         The InetAddress...getHostName() call will use the DNS databases.
RL> For most computers, however, this won't return anything useful.

That is not true. Most of US IPs have PTR records. That includes your
own IP, that you had when sending your msg. By far, most servers have rDNS,
most dynamic IPs do, most static IPs for cable/DSL do, and even most routers
do.

Asia (particularly Taiwan, China and Korea) is probably the worst, as
far as being able to to rDNS. But even they might be a little over
50%, especially Japan.

RL>         Randy

>> -----Original Message-----
>> From: David Wall [mailto:dwall@myEastside.com]
>> Sent: Friday, July 06, 2001 12:02 AM
>> To: tomcat-user@jakarta.apache.org
>> Subject: 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
>> 
>> 



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