* cookie controls. See <a href="http://www.ietf.org/rfc/rfc2109.txt">RFC 2109</a> for details.
   *
   * @since 6.0
   */
  public boolean isTopPrivateDomain() {
    return publicSuffixIndex() == 1;
  }

  /**
   * Returns the portion of this domain name that is one level beneath the {@linkplain

      assertTrue(name, domain.isPublicSuffix());
      assertTrue(name, domain.hasPublicSuffix());
      assertFalse(name, domain.isUnderPublicSuffix());
      assertFalse(name, domain.isTopPrivateDomain());
      assertThat(domain.publicSuffix()).isEqualTo(domain);
    }

    for (String name : NO_PS) {
      InternetDomainName domain = InternetDomainName.from(name);

      assertTrue(name, domain.isPublicSuffix());
      assertTrue(name, domain.hasPublicSuffix());
      assertFalse(name, domain.isUnderPublicSuffix());
      assertFalse(name, domain.isTopPrivateDomain());
      assertThat(domain.publicSuffix()).isEqualTo(domain);
    }

    for (String name : NO_PS) {
      InternetDomainName domain = InternetDomainName.from(name);