#!/usr/bin/perl

use warnings;
use strict;
$|++;

use JSON;

my $l;
my @vals;
my $json;
my %pairs;

while (<>) {
    $l = $_;
    chomp $l;
    @vals = split /;/, $l;
    if ($vals[0] =~ /Query/) {
        $pairs{$vals[1]}{$vals[2]} = $vals[3];
    } elsif ($vals[0] =~ /Answer/) {
        $pairs{$vals[1]}{$vals[2]} = $vals[3];
        $json = encode_json $pairs{$vals[1]};
        print $json."\n";
        delete $pairs{$vals[1]};
    }
}

##</code><code>##

[root@hadron ~]# ./t-1207429.pl t-1207429.txt
{"ip":"1.2.3.4","host":"www.example.com"}
{"ip":"2.3.4.5","host":"www.cnn.com"}
{"ip":"3.4.5.6","host":"www.google.com"}