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Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!uc!cs.umn.edu!ux.acs!aaron
From: aaron@ux.acs.umn.edu (Aaron Y.T. Cheung)
Newsgroups: comp.unix.admin,comp.unix.misc,comp.unix.questions
Subject: Re: name server
Keywords: hostname, reverse-mapping, ptr, nslookup, nameservers
Message-ID: <2210@ux.acs.umn.edu>
Date: 10 Sep 90 08:33:48 GMT
References: <90252.231430TOMIII@MTUS5.BITNET>
Reply-To: aaron@ux.acs.umn.edu (Aaron Y.T. Cheung)
Followup-To: comp.unix.questions
Organization: University of Minnesota, Academic Computing Services
Lines: 28


| Does anyone know how to obtain the hostname of a machine given the IP
| address using a name server (the nslookup feature of unix?) ?


Try the reverse mapping -- nslookup with the PTR type:

Eg, to get the hostname of IP address 128.101.63.2,

nslookup> set q=ptr
nslookup> 2.63.101.128.in-addr.arpa.    (note that the IP is supplied reversed)

for the convenience of querying multiple IP's, 

nslookup> set q=ptr
nslookup> set do=in-addr.arpa.
nslookup> 2.63.101.128
nslookup> 1.63.101.128
etc.

Works only if the IP address is connected to the Internet and someone
did register his corresponding network.in-addr.arpa domain with Nic
and someone actually put in the ptr records for their hosts and their
primary and secondary nameservers are not down and.... :-)

Hope it helps.

/aaron.