Behavior of nslookup

So I was playing with nslookup on some bogus addresses, for a script.
and I ended up getting some unexpected behavior.

Code:

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IP="192.168.1.1"
nslookup $IP

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Quote:

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Lookup failedServer: A_vaild_address*
Address: A_vaild_address


** server can't find 1.1.168.192.in-addr.arpa.: NXDOMAIN

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The IP used in the NXDOMAIN field is backwards. Is this the normal convention for looking up domain names from IP's?

*same results on different DNS servers

It's normal. "in-addr.arpa" is special domain for reverse DNS, in the syntax field must be backwards.
http://en.wikipedia.org/wiki/In-addr.arpa

Thank you for the help.

If you haven't seen it yet, there is also dig. It can do a lot more but is also good for basic lookups.