DNS "A" query for a single dot

[Chris Thompson]

On Mar 11 2008, Barry Margolin wrote:

>In article <fr4vdl$2c7l$1 at sf1.isc.org>, Mark <anonymoususr at gmail.com> 
>wrote:
>
>> Hello ,
>> 
>> Does anybody knows what an "A" query for a dot (".") means?
>
>"." is the root domain.
>
>> Is it part of DNS and serve a special purpose?
>> Is it a bug on the client making the query?
>> Is it an indicative of a bot/worm making queries?
>> 
>> I am parsing the DNS packet using the name server library (function
>> ns_initparse) and some  DNS packets have questions for "."
>
>I think there are a number of domains that have MX records pointing to 
>the root, as a convention to prevent mail from being sent to the domain.

Positive incentive for some Evil Root Zone Administrator to set up
an A record and trap all that e-mail, isn't it? No wildcard needed!

I also seem to recall lookups for (IN,A,".") being used by monitoring
software to test whether nameservers are up or not. Not the best choice, 
I thought.

-- 
Chris Thompson
Email: cet1 at cam.ac.uk