Query Regarding CNAMES

[Joseph S D Yao]

On Mon, May 24, 2010 at 05:07:02PM +0530, Ashwin wrote:
> Hi All,
> 
> I had a general query regarding CNAME RR's
> 
> Supposing I do an A query for aaa.com
> 
> Is the following response possible?
> 
> Response:
> aaa.com IN CNAME bbb.com
> bbb.com IN CNAME ccc.com
> ccc.com IN CNAME ddd.com
> 
> Essentially whether CNAME chaining can be present in a single response from
> the server. 
...


This depends on how the server you're querying is set up.

The above query would have to go to the .com name server, since it's
impossible to have a CNAME record for the domain and then delegate the
domain to another name server.  Specifically, in your example, there can
not be name servers for "aaa.com", "bbb.com", and "ccc.com".

If you're directly querying an authoritative name server for the domain,
and if that authoritative name server is configured to not allow
recursive resolution, and the chain goes off that name server, then the
chain is broken and will not continue.


--
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** Joe Yao				jsdy at tux.org - Joseph S. D. Yao
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