When I try to do an ls for a reverse map it doesn't list.

NOTE: You cannot use ls on our DNS server from non 129.6
      addresses.

[sean@phantom acsl]$ nslookup
Default Server:  dove.nist.gov
Address:  129.6.2.2

> ls 182.6.129.in-addr.arpa
[dove.nist.gov]
$ORIGIN 182.6.129.IN-ADDR.ARPA.

vs. on Solaris or Irix

> ls 182.6.129.in-addr.arpa
[dove.nist.gov]
 182.6.129.IN-ADDR.ARPA.        server =
dove.nist.gov
 182.6.129.IN-ADDR.ARPA.        server =
hawk.nist.gov
 113                            host =
h182113.nist.gov
 114                            host =
h182114.nist.gov
 115                            host =
h182115.nist.gov
 116                            host =
h182116.nist.gov
 117                            host =
wave.nist.gov
 120                            host =
zeus-s.nist.gov
 118                            host =
h182118.nist.gov
 121                            host =
zeus-p.nist.gov
 119                            host =
thunder.nist.gov
 122                            host =
ose1.nist.gov
 123                            host =
lift.nist.gov
 124                            host =
h182124.nist.gov
 125                            host =
h182125.nist.gov
 126                            host =
taurus.nist.gov
 130                            host =
phantom.nist.gov
 128                            host =
ipsg4000.nist.gov
 131                            host =
shaken.nist.gov
 129                            host =
toy.nist.gov
 132                            host =
melba.nist.gov
....