sub validate_hostname{
	my $candidate = shift;
	my ($ascii_only, $verbose, $debug) = @_; # leave room for improvments and flexibility
	my ($return, $descr);
	
        # non ASCII
	if ( $candidate =~ m/[^[:ascii:]]/ ) {   # but see: https://perlmonks.org/?node_id=11164574
		print "Not ACSII\n" if $verbose;
		# ..accepted?
		if ($ascii_only){
			return wantarray ? (undef,"non ASCII string [$candidate] rejected") : undef;
		}
		# go with another specialized sub..
		validate_hostname_Unicode($candidate,$ascii_only, $verbose, $debug );	
	} 
	# ASCII
	
	# too long..
	if (length $candidate >= 255){
		$descr =  "[$candidate] is too long (".length $candidate." chars)";
		print $descr if $verbose;
		return wantarray ? (undef,$descr) : undef;
	}
	# Hostnames might be composed by 1 or more labels (separated by dots)
	unless ($candidate =~ /\./){
		$descr =  "[$candidate] contains no dots";
		print $descr if $verbose;
		return wantarray ? (undef,$descr) : undef;
	}
        # .. more checks for this rule

	# Each label may have at most 63 characteres
	...
	#..have fun :)
}