diff -Nurp samba-4.9.1/python/samba/tests/dcerpc/dnsserver.py samba-4.9.1-bak/python/samba/tests/dcerpc/dnsserver.py
--- samba-4.9.1/python/samba/tests/dcerpc/dnsserver.py	2019-07-29 11:56:23.948000000 -0400
+++ samba-4.9.1-bak/python/samba/tests/dcerpc/dnsserver.py	2019-07-29 11:58:35.410000000 -0400
@@ -731,6 +731,32 @@ class DnsserverTests(RpcInterfaceTestCas
         # We should always encounter a DOES_NOT_EXIST error.
         self.fail()
 
+    # This test is to confirm that we do not support multizone operations,
+    # which are designated by a non-zero dwContext value (the 5th argument
+    # to DnssrvOperation2).
+    def test_operation2_invalid(self):
+        client_version = dnsserver.DNS_CLIENT_VERSION_LONGHORN
+        non_zone = 'a-zone-that-does-not-exist'
+        typeid = dnsserver.DNSSRV_TYPEID_NAME_AND_PARAM
+        name_and_param = dnsserver.DNS_RPC_NAME_AND_PARAM()
+        name_and_param.pszNodeName = 'AllowUpdate'
+        name_and_param.dwParam = dnsp.DNS_ZONE_UPDATE_SECURE
+        try:
+            res = self.conn.DnssrvOperation2(client_version,
+                                             0,
+                                             self.server,
+                                             non_zone,
+                                             1,
+                                             'ResetDwordProperty',
+                                             typeid,
+                                             name_and_param)
+        except WERRORError as e:
+            if e.args[0] == werror.WERR_DNS_ERROR_ZONE_DOES_NOT_EXIST:
+                return
+
+        # We should always encounter a DOES_NOT_EXIST error.
+        self.fail()
+
     def test_operation2(self):
         client_version = dnsserver.DNS_CLIENT_VERSION_LONGHORN
         rev_zone = '1.168.192.in-addr.arpa'
diff -Nurp samba-4.9.1/source4/rpc_server/dnsserver/dcerpc_dnsserver.c samba-4.9.1-bak/source4/rpc_server/dnsserver/dcerpc_dnsserver.c
--- samba-4.9.1/source4/rpc_server/dnsserver/dcerpc_dnsserver.c	2019-07-29 11:56:23.950000000 -0400
+++ samba-4.9.1-bak/source4/rpc_server/dnsserver/dcerpc_dnsserver.c	2019-07-29 12:00:03.852000000 -0400
@@ -2168,7 +2168,12 @@ static WERROR dcesrv_DnssrvOperation2(st
 						&r->in.pData);
 	} else {
 		z = dnsserver_find_zone(dsstate->zones, r->in.pszZone);
-		if (z == NULL && request_filter == 0) {
+               /*
+                * In the case that request_filter is not 0 and z is NULL,
+                * the request is for a multizone operation, which we do not
+                * yet support, so just error on NULL zone name.
+                */
+               if (z == NULL) {
 			return WERR_DNS_ERROR_ZONE_DOES_NOT_EXIST;
 		}