I never believed URLs could have a period at the end, as in www.google.de. (which obvious is not working).However, www.youtu.be. is working perfectly well. How did they manage that?
How can URLs have a dot . at the end, e.g. www.bla.de.?
domains;url
From hereIt's a little-known fact, but fully-qualified (unambiguous) DNS domain  names have a dot at the end. People running DNS servers usually know  this (if you miss the trailing dots out, your DNS configuration is  unlikely to work) but the general public usually doesn't. A domain  name that doesn't have a dot at the end is not fully-qualified and is  potentially ambiguous. This was documented in the DNS specification,  RFC 1034, way back in 1987:Since a complete domain name ends with the root label, this leads to a  printed form which ends in a dot.  We use this property to distinguish  between:a character string which represents a complete domain name   (often called absolute).  For example, poneria.ISI.EDU.a character string that represents the starting labels of a   domain name which is incomplete, and should be completed by   local software using knowledge of the local domain (often   called relative).  For example, poneria used in the   ISI.EDU domain. The source of this content continues to explain this in more detail.