if (domains == null) {
            return false;
        }
        domain = domain.toLowerCase();
        return domains.get(domain) != null;
    }

    /**
     * Gets a domain controller transport for the specified domain
     * @param domain the domain name
     * @param auth the authentication credentials
     * @return an SMB transport to the domain controller

        synchronized (this.domainsLock) {
            final Map<String, Map<String, CacheEntry<DfsReferralDataInternal>>> domains = getTrustedDomains(tf);
            if (domains == null) {
                return false;
            }
            domain = domain.toLowerCase(Locale.ROOT);
            return domains.get(domain) != null;
        }
    }

   * </ul>
   *
   * @param domain A domain name (not IP address)
   * @throws IllegalArgumentException if {@code domain} is not syntactically valid according to
   *     {@link #isValid}
   * @since 10.0 (previously named {@code fromLenient})
   */
  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
  public static InternetDomainName from(String domain) {
    return new InternetDomainName(checkNotNull(domain));

    }

    @ParameterizedTest
    @MethodSource("domains")
    @DisplayName("getUserDomain handles null and empty")
    void getUserDomain_edges(String domain) {
        TestCredentials creds = new TestCredentials(domain, false, false, new Subject(), false);
        assertEquals(domain, creds.getUserDomain());
    }

    static Stream<String> domains() {
        return Stream.of(null, "", "SALES");
    }

        public LsarTrustInformation[] domains;
        /** Maximum count of domains. */
        public int max_count;

        @Override
        public void encode(NdrBuffer _dst) throws NdrException {
            _dst.align(4);
            _dst.enc_ndr_long(this.count);
            _dst.enc_ndr_referent(this.domains, 1);
            _dst.enc_ndr_long(this.max_count);

            if (this.domains != null) {

    /**
     * Construct a relative SID
     *
     * @param domsid the domain SID
     * @param id the SID to append to the domain SID
     */
    public SID(final SID domsid, final SID id) {
        this.revision = domsid.revision;
        this.identifier_authority = domsid.identifier_authority;
        this.sub_authority_count = (byte) (domsid.sub_authority_count + id.sub_authority_count);

        // Test User SID (type 1)
        assertEquals("1Test User", sambaHelper.getAccountId(createMockSID(1, "Test User")));

        // Test Domain Group SID (type 2)
        assertEquals("2Domain Group", sambaHelper.getAccountId(createMockSID(2, "Domain Group")));

        // Test Alias SID (type 4, mapped to 2)
        assertEquals("2Local Group", sambaHelper.getAccountId(createMockSID(4, "Local Group")));

        }

        @Test
        @DisplayName("Should fixup domain")
        void testFixupDomain() {
            String domain = "example.com";

            // Test with mock
            doNothing().when(mockReferralData).fixupDomain(domain);
            mockReferralData.fixupDomain(domain);
            verify(mockReferralData, times(1)).fixupDomain(domain);

    @Test
    @DisplayName("Test constructor with domain and server types")
    void testConstructor() {
        String domain = "WORKGROUP";
        int serverTypes = NetServerEnum2.SV_TYPE_ALL;

        netServerEnum2 = new NetServerEnum2(realConfig, domain, serverTypes);

        assertNotNull(netServerEnum2);
        assertEquals(domain, getFieldValue(netServerEnum2, "domain"));

* **TCP doesn't know about "domains"**. Only about IP addresses.
    * The information about the **specific domain** requested goes in the **HTTP data**.
* The **HTTPS certificates** "certify" a **certain domain**, but the protocol and encryption happen at the TCP level, **before knowing** which domain is being dealt with.