while(<DATA>) {
    if (/(\d+)\.(\d+)\.(\d+)\.(\d+)/) { 
        print "$1.$2.$3.$4 ";
        if ($1<256 and $2<256 and $3<256 and $4<256) {
           print "is IP\n";
        } else {
           print "is not an IP\n";
        }  
    }
}
__DATA__
0.0.0.0
255.255.255.255
1.2.3.4
256.1.1.1