* parent domain for which cookies may be set. Use {@link #topPrivateDomain()} for that purpose.
   *
   * @since 23.3
   */
  public boolean isTopDomainUnderRegistrySuffix() {
    return registrySuffixIndex() == 1;
  }

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

      assertTrue(name, domain.isRegistrySuffix());
      assertTrue(name, domain.hasRegistrySuffix());
      assertFalse(name, domain.isUnderRegistrySuffix());
      assertFalse(name, domain.isTopDomainUnderRegistrySuffix());
      assertThat(domain.registrySuffix()).isEqualTo(domain);
    }

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

      assertTrue(name, domain.isRegistrySuffix());
      assertTrue(name, domain.hasRegistrySuffix());
      assertFalse(name, domain.isUnderRegistrySuffix());
      assertFalse(name, domain.isTopDomainUnderRegistrySuffix());
      assertThat(domain.registrySuffix()).isEqualTo(domain);
    }

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