I'm not sure of your input file but this should get you started in the right direction, if not maybe someone can learn a tip of two. HAVE FUN!

#!/usr/bin/perl-w

use strict;
use win32;

my $in_name=$ARGV[0];
my $out_name=$ARGV[1];

our (@x);  # new type of global declaraton
           # carefull commas needed I.E. our (@x, @y);
           # use vars qw ( @x @y );  <- obsolete global declaration

# pass a reminder
if($#ARGV < 1) {
  die "usage: ip.pl <input file> <output file>\n"
    . "for example: program.pl infile.txt outfile.txt\n"
}

open(FILE, $in_name) || die "ip.pl can't open $in_name: $!";
open(IPFILE,">$out_name") || die "ip.pl can't open $out_name: $!";

my $dns2="toto";   #157.173.20.2
my $dns3="oz";     #157.173.20.3
my $dns4="wizard"; #157.173.20.4

my $ip2;
my $ip3;
my $ip4;

while (<FILE>){
    # sample line 
    # Tz25,D,wizard,2,157.173.20.2,Local
    
    @x=split(/,/);
    next unless (($_ =~ /Local/)||($_ =~ /Network/));
    
    if  ($x[4] =~ /157.173.20.2/){ 
        $ip2 = $dns2;
        print $x[0], $x[1], $x[2], $ip2;
        print IPFILE;
    }
}
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