#!/usr/bin/perl -w

use Data::Dumper;

while(<DATA>)
{
	chomp;
	next unless $_;
	if($_ =~ /^\d+\.\d+\.\d+\.\d+/) 
	{
		push @{$CoreRegR{$key}},$_;
		# first time, for new server, auto-vivifies
		# $CoreRegR{$key} as arrayref.		
		# first and all other times,		
		# pushes the ip range onto the anon array that
		# $CoreRegR{$key} refers to.
	}
	else 
	{
		$key = $_;
	} 
}

print Dumper(\%CoreRegR);

__DATA__
Server1 Name
192.168.100.1/27
192.168.101.2/32
Server2 Name
Server3 Name
192.168.102.3/31
192.168.103.4/30
192.168.104.5/28
Server4 Name
10.100.2.1/31
10.101.2.2/32
10.102.2.3/28
Server5 Name
10.103.2.4/29
10.104.2.5/27

##</code><code>##

$VAR1 = {
          'Server3 Name' => [
                              '192.168.102.3/31',
                              '192.168.103.4/30',
                              '192.168.104.5/28'
                            ],
          'Server4 Name' => [
                              '10.100.2.1/31',
                              '10.101.2.2/32',
                              '10.102.2.3/28'
                            ],
          'Server5 Name' => [
                              '10.103.2.4/29',
                              '10.104.2.5/27'
                            ],
          'Server1 Name' => [
                              '192.168.100.1/27',
                              '192.168.101.2/32'
                            ],
          'Server2 Name' => []
        };