[Dnsmasq-discuss] CNAME

Simon Kelley simon at thekelleys.org.uk
Fri Jan 27 14:56:16 GMT 2006

Merlin wrote:
> Hi, Simon,
> Thanks for the detailed explanation. I think I understand now!
> But would it not be possible achieve roughly the same functionality 
> within the dnsmasq architecture (without using CNAMEs) if there were 
> some sort of configuration option that says a lookup of "foo" should 
> always be proxied to the upstream server(s) as a lookup of "bar" 
> instead? (Kind of a name based version of the --alias option instead of 
> the current IP based version?)
> Merlin

Doing that suffers from the same sort of problems: It would  be easy to 
re-write the query as "bar" instead of "foo", but then the answer would 
come back as "bar is" Sending that answer back to the original 
requestor will get you nowhere: it asked for the A record for "foo" and 
will ignore an answer for "bar". So the re-write would have be reversed 
on the way back throught dnsmasq. That means keeping re-write 
information for all in-progress queries. That changes the current 
datastructure for in-progress queries from a fixed-size table mapping 
query-id to original source into a dynamically allocated monster with 
large records. By now you're re-writing BIND.



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