From IP to domain name

["Ivan J. Varzinczak" <ivan@inf.ufpr.br>]

Hi, everybody!

	I'd like to know if someone can give me any sugestions about
how I can discover the domain name given an IP address. For example,
if I have the IP address 205.188.146.23, I would like to discover what 
the domain name is, in that case, aol.com.
	I've tried to use nslookup, but I've had some problems in
setting the servers, because perhaps I'll need the "root" servers on
internet and it doesn't work very well.
	Thanks in advance!
-- 
Ivan J. Varzinczak - http://www.inf.ufpr.br/~ivan
Scholarship holder - Boursier - (PET/CAPES)
Informatics Department - Département d'Informatique
Federal University of Paraná - Université Fédérale du Paraná
Curitiba - Paraná - Brazil/Brésil

10-V-2000