reverse nslookup

[Joop Joosten]

Hi all,
I found on the web several sites that resolve a name in an IPv6 address.
However, I did not find anywhere a place that allows me to resolve an
IPv6 address in a name. Such a "service" would allow me to check if the
reverse delegation is functioning. 
Can anybody give me a pointer to such a facility? 
Thanks, Joop.

 +-----------------------------------------------------------------------+
 |     Joop Joosten, IT Division, CERN, 1211 Geneva 23, Switzerland      |
 |Tel: +41 22 767 3361;  Fax: +41 22 767 7155;  E-M: Joop.Joosten@cern.ch|
 +-----------------------------------------------------------------------+