[Gllug] DNS CNAME usage.

[Stephen Harker]

Hi All,

Does anyone have an opinion about CNAME usage and using a CNAME record 
to refer to a canonical name that is not part of the current domain and 
whether there should be problems associated with this?

For instance.

www.foo.com	IN	CNAME	foo.bar.com

I have been reading up the RFCs and can't find anything problematic yet.

The reason I ask, is that we have several customers that have their 
domains set up like this and recently (the last week or so) SOME people 
have been having difficulties resolving the CNAME to an IP address.

It all works fine when I use dig or host to query www.foo.com.

;; QUESTION SECTION:
;www.foo.com.                IN      A

;; ANSWER SECTION:
www.foo.com. 9428    IN      CNAME   foo.bar.com.
foo.bar.com.   2195    IN      A       10.4.78.22

(names changed to protect the innocent)

It seems to be isolated offices around the place that are having 
difficulty. Needless to say, none of the people I have spoken to at the 
affected sites have been technical enough to be very forthcoming with 
detailed error messages, but they are getting the IE/Firefox "Can't find 
  Server" error message which translates as an error in DNS lookup. I am 
trying to get some more detail but haven't yet managed to get anything 
more helpful than this. My initial suspicion is that, perhaps, Microsoft 
had released some Service Pack or Windows Update that breaks DNS but I 
can't get hold of a Windows machine to check.

Sorry for the rambling but it's an otherwise quiet Friday and I'm puzzled.

Stephen
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