> 3de.doubleclick.net is delegated to 4 nameservers
> ({uk,de,fr,se}3dns1.doubleclick.net), but each of them only publishes a
> single {uk,de,fr,se}3dns1.3de.doubleclick.net NS record for the zone. In
> other words, if you happen to query, say, fr3dns1.doubleclick.net for
> the NS record of the 3de.doubleclick.net zone, it would respond with
> only an NS record pointing to fr3dns1.3de.doubleclick.net.

they have (semi-)fixed the problem already at the time you wrote your
post, now they point at least to _one_ existing host.

At the time I wrote my posting the situation was this:

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++
# dig 3de.doubleclick.net @se3dns1.doubleclick.net ns

; <<>> DiG 8.3 <<>> 3de.doubleclick.net @se3dns1.doubleclick.net ns
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60330
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; 3de.doubleclick.net, type = NS, class = IN

3de.doubleclick.net. 1W IN NS
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++

The unresolvable host (no A-Record)
was the reason for the timeout of bind8.
Now after the correction, there is no timeout issue anymore.

But your absolutly right with this one:

> Ultimately, doubleclick.net needs to fix either their delegations or
> their in-zone NS records for 3de.doubleclick.net. The in-zone NS records
> should match the delegation NS records. At a bare minimum, they need to
> follow Internet standards and publish at least 2 NS'es for the zone.