<?php
$ip = '173.27.5.10';
$list = '78.20.16.0/20 Net1
81.254.224.0/20 Net1
173.21.0.0/17 Net10
173.9.2.0/22 Net1
10.15.26.0/20 Net2
173.27.0.0/16 Net3
95.74.197.0/18 Net1
22.33.224.0/24 Net7';
$template = '~(\d+\.\d+\.\d+\.\d+)/\d+\s+(.+)~';
preg_match_all($template, $list, $regular);
for($i = 0; $i < sizeof($regular[0]); $i++) {
	if(preg_match('~^'.str_replace('.', '\.', preg_replace('~(\.?)0(\.?)~', '$1\d+$2', $regular[1][$i])).'$~', $ip)) {
		echo $regular[2][$i];
		break;
	}
}
?>