Re: forward and reverse dns lookups (not linux related)

Reverse and forward queries can use UDP or TCP. Does reverse always fail? Reverse DNS resolution is not required and many networks don't configure it. How do you do the reverse lookups (copy / paste the command line) . For example with "dig" , you use either the -x option, or you manually "reverse" the IP address and add the in-addr.arpa domain. "Host" will swap things automatically.

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Johannes B. Ullrich
SANS Technology Institute
[email protected]

On Nov 9, 2012, at 3:20 PM, The Donald Cowart <[email protected]> wrote:

> Just off the top of my head, one is using TCP, the other UDP???
> 
> --DC
> 
> 
> On Fri, Nov 9, 2012 at 4:17 PM, Robert Mckennon <[email protected]>wrote:
> 
>> So...the issue is:
>> 
>> Connected to the coorporate network via a vpn connection through our
>> new cisco ASA, for some reason Forward DNS queries fail, but Reverse
>> DNS queries work....  This is very baffling!
>> 
>> I just can't image that the fire somehow is blocking forward lookups
>> but allowing reverse lookups, when icmp and filesharing all work (at
>> least via ip address).
>> 
>> 
>> Any thoughts???
>> 
>> Rob.
>> 
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> 
> -- 
> Donald Cowart
> http://www.rdex.net/

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