serverside url validation

Description of problem:
I want to validate urls serversideusing code like this:

            Field::inst( 'NameOfField' )
                    ->validator( Validate::url( 
                                                  ValidateOptions::inst()
                                  ->message( 'ErrorMessage' )
                ) )

With this I encounter several oddities: in my tests

• http://bremen.de => validates ok => correct
• https://bremen.de => validates ok => correct
• bremen.de => validates not ok => correct
• http:bremen.de => validates not ok => correct
• htt://bremen.de => validates ok => not correct ?
• http://bremen => validates ok => not correct ?

What do I do wrong?

Or is this behaviour intentional? I read you are using a library (https://www.npmjs.com/package/valid-url/v/1.0.3), and they say it validates "relatively 'real-world' " ...

As a workaround I did some experiments with 'pinging' the adresses, which works, but not solid rock - so it would be very nice if someone could help me out.