classless in-addr.arpa delegation & hidden (stealth) primary

[Frank Joerdens]

I am running a stealth (hidden) primary (ns.archi-me-des.de) where the
primary and secondary at our upstream provider's are

ns.internet.de
ns2.internet.de

The IP address to hostname mappings for our domains work fine; however,
this hidden primary setup does not, but is supposed to work also, for the
in-addr.arpa delegation for our network, which is

64/28.107.103.212.in-addr.arpa

I am trying to figure out whether the problem is at our end or at the
upstream provider's. If I ask my nameserver for the zone, I get:

------------------------------ snip ------------------------------
$ nslookup - ns.archi-me-des.de
Default Server:  ns.archi-me-des.de
Address:  212.103.107.70
Aliases:  70.107.103.212.in-addr.arpa

> set ty=ptr
> 70.107.103.212.in-addr.arpa
Server:  ns.archi-me-des.de
Address:  212.103.107.70
Aliases:  70.107.103.212.in-addr.arpa

70.107.103.212.in-addr.arpa     canonical name =
70.64/28.107.103.212.in-addr.arpa
70.64/28.107.103.212.in-addr.arpa       name = ns.archi-me-des.de
64/28.107.103.212.in-addr.arpa  nameserver = ns.internet.de
64/28.107.103.212.in-addr.arpa  nameserver = ns2.internet.de
ns.internet.de  internet address = 212.27.128.70
ns2.internet.de internet address = 212.103.97.133
> 64/28.107.103.212.in-addr.arpa
Server:  ns.archi-me-des.de
Address:  212.103.107.70
Aliases:  70.107.103.212.in-addr.arpa

64/28.107.103.212.in-addr.arpa
        origin = ns.archi-me-des.de
        mail addr = frank.joerdens.de
        serial = 2001081701
        refresh = 3600 (1H)
        retry   = 1800 (30M)
        expire  = 6048000 (10W)
        minimum ttl = 3600 (1H)
------------------------------ snap ------------------------------

Which looks good to me. If I ask the actual primary (which should have
my hidden listed as a stealth primary) though, I get:

------------------------------ snip ------------------------------
$ nslookup - ns.internet.de
Default Server:  ns.internet.de
Address:  212.27.128.70

> set ty=ptr
> 64/28.107.103.212.in-addr.arpa
Server:  ns.internet.de
Address:  212.27.128.70

*** ns.internet.de can't find 64/28.107.103.212.in-addr.arpa:
Non-existent host/domain
------------------------------ snap ------------------------------

As I understand rfc2317, the server ns.internet.de should have a zone
file which lists the domain 64/28.107.103.212.in-addr.arpa as being
delegated by ns.archi-me-des.de. May I assume, since the above query
fails, that this is not the case and that therefore the fault is at my
upstream provider's?

Thanks, Frank