use strict;

my %ip_company;

open( I, "File1" ) or die "File1: $!";
while (<I>)
{
    chomp;
    my ( $company, $bgn_IP, $end_IP ) = split /-/;

    next unless ( $bgn_IP =~ /^(\d+\.\d+\.)(\d+)\.\d+$/ );
    my ( $bgn_q12, $bgn_q3 ) = ( $1, $2 );
    next unless ( $end_IP =~ /^(\d+\.\d+\.)(\d+)\.\d+$/ );
    my ( $end_q12, $end_q3 ) = ( $1, $2 );
   # NB: if $bgn_q12 ne $end_q12, we need some different logic...

    $ip_company{$bgn_q12.$bgn_q3} = $company;
    if ( $bgn_q3 != $end_q3 ) {
        for my $next_q3 ( $bgn_q3+1 .. $end_q3 ) {
            $ip_company{$bgn_a12.$next_q3} = $company;
        }
    }
}

open( I, "File2" ) or die "File2: $!";
while (<I>)
{
    chomp;
    ( my $lookup = $_ ) =~ s/\.\d+$//;
    if ( exists( $ip_company{$lookup} )) {
        print "$_ is part of $ip_company{$lookup}\n";
    } else {
        print "$_ is not part of any known company\n";
    }
}