* controls. See <a href="http://www.ietf.org/rfc/rfc2109.txt">RFC 2109</a> for details.
   *
   * @since 6.0
   */
  public boolean isUnderPublicSuffix() {
    return publicSuffixIndex() > 0;
  }

  /**
   * Indicates whether this domain name is composed of exactly one subdomain component followed by a