child and forwarder

[JULIEN Antoine]

    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?

                                                                Thanks