code: @Override
    public boolean isResolvable(String host) {
      try {
        InetAddress.getByName(host).getHostAddress();
        return true;
      } catch (UnknownHostException ex) {
        log.log(Level.FINE, "Hostname not resolveable {0}.", host);
      }
      return false;
    }
docs: ***********************************************************************
  Tries to resolve the host name. Returns true if succeeds.
  
  @param host
  is the host name from the URL.
  @return true if resolvable else false.
  **********************************************************************