I’m always wondering if the addresses I’m assigning to interfaces aren’t already in DNS. So I came up with a little BASH script that takes a list of IP addresses and performs an nslookup on them to ensure they’re not in use already:
$nslookup < input-filename > output-filename
The addresses in the input file are carriage return delimited.
A better use for this would be to check if DNS entries already have an IP address assigned to them.