child and forwarder

[Michael Voight]

JULIEN Antoine wrote:
> 
>     I have a DNS (called "parent DNS") config with a forwarder to redirect
> request outside my domain. I install a child DNS (under "parent DNS") for a
> subdomain (I add NS and A RR on "parent DNS"), all work fine. But, when I
> watch the network with tcpdump, I see (the command is a nslookup on parent
> machine: lookup for the child machine):
> 
>     1) a connection between the parent DNS and his forwarder
>     2) a connection between the forwarder and the child DNS
>     3) a connection between the child and forwarder
>     4) and the response is given by the forwarder to the parent DNS
> 
>     Why is this so complicated? Why the parent don't address directly his
> request to the child?
> 

Because, if you specify a forwarder, ALL requests for records you don't
have (like an A record in the subzone) go to the forwarder. This is how
DNS was designed to work.  In the beginning, a top level server
(something.com) would NOT have a forwarder.
In the beginning, the top level server went to the root servers to
resolve other zones. Now, with ISP's this has changed to reduce traffic.

BIND V8 will let you selectively forward. Bing V4 doesn't.

Michael Voight