code: private static boolean isHostDnsName(URI uri) {
          String host = uri.getHost();
          for (int i = 0; i < host.length(); i++) {
              char hostChar = host.charAt(i);
              if (!Character.isDigit(hostChar) && !(hostChar == '.')) {
                  return true;
              }
          }
          return false;
      }
docs: Returns a boolean indicating whether the host of the specified URI is DNS.
  
  @param uri
  The URI whose host to evaluate.
  @return <code>true</code> if the host is DNS; otherwise, <code>false</code>.