[dns-operations] A lot of CNAME queries for domain ?

Mohamed Lrhazi ml623 at georgetown.edu
Thu Jul 5 17:17:28 UTC 2012


Yeah... I did read somewhere recently that some SMTP RFC does say the mail
server should query for the CNAME record, but only if MX record was not
found....

I still don't understand why I see so many such queries... This is bigger
issue because I just found out my DNS server is generating a malformed
packet, as a response to these specific queries...

Mohamed.

On Thu, Jul 5, 2012 at 12:43 PM, Simon Munton <Simon.Munton at communitydns.net
> wrote:

> That sounds odd to me as CNAME records are not normally ever specifically
> queried (asked) for.
>
> Where they exist, they are given as reply to a query for any RR type, but
> the CNAME itself is then followed by the resolver until an answer is
> achieved.
>
> e.g.
>
> authority => www IN CNAME web1
>
> query     => www/IN/A
>
> reply     => www IN CNAME web1
>
> You don't actually ask for the CNAME, in that respect its similar to a
> wildcard. In my little example, we asked for an "A" records, but were given
> the CNAME.
>
>
> On 05/07/2012 15:32, Mohamed Lrhazi wrote:
>
>> Hello all,
>>
>> If this is not an appropriate question for the list, please accept
>> my apologies and please suggest a better one.
>>
>> I just started administering DNS for my organisation and I notice in the
>> query logs a lot of queries of type CNAME for our domain, say,
>> example.com <http://example.com>
>>
>>
>> We do not have such a record and so these queries get an empty answer.
>>
>> I am just curious what applications out there would be generating such
>> queries... Please note that we do have an MX record for the domain and
>> also an A record.
>>
>> Thanks a lot,
>> Mohamed.
>>
>>
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