Well, according to my nslookup, it only takes one host at a time, not a whole list of them. That said, though, you could just loop through the IPs and use backticks to call nslookup on each one:

for my $ip (@ips) {
    my $output = `nslookup $ip`;
}
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In general, if you need the output of a command, use backticks; if you don't, use system.

However, in this case, you should probably just use Perl builtins or the Socket module, if possible. For example, to translate a host name into an IP address:

use Socket;
my $addr = inet_ntoa scalar gethostbyname $host;
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