diff --git a/bin/named/main.c b/bin/named/main.c
index 4cb4846310..aa131988b0 100644
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -122,14 +122,17 @@ static int		maxudp = 0;
  */
 static bool clienttest = false;
 static bool dropedns = false;
-static bool noedns = false;
-static bool nosoa = false;
-static bool noaa = false;
-static unsigned int delay = 0;
-static bool nonearest = false;
-static bool notcp = false;
+static bool ednsformerr = false;
+static bool ednsnotimp = false;
+static bool ednsrefused = false;
 static bool fixedlocal = false;
+static bool noaa = false;
+static bool noedns = false;
+static bool nonearest = false;
+static bool nosoa = false;
+static bool notcp = false;
 static bool sigvalinsecs = false;
+static unsigned int delay = 0;
 
 /*
  * -4 and -6
@@ -488,6 +491,12 @@ parse_T_opt(char *option) {
 		dropedns = true;
 	} else if (!strncmp(option, "dscp=", 5)) {
 		isc_dscp_check_value = atoi(option + 5);
+	} else if (!strcmp(option, "ednsformerr")) {
+		ednsformerr = true;
+	} else if (!strcmp(option, "ednsnotimp")) {
+		ednsnotimp = true;
+	} else if (!strcmp(option, "ednsrefused")) {
+		ednsrefused = true;
 	} else if (!strcmp(option, "fixedlocal")) {
 		fixedlocal = true;
 	} else if (!strcmp(option, "keepstderr")) {
@@ -547,7 +556,7 @@ parse_T_opt(char *option) {
 	} else if (!strncmp(option, "tat=", 4)) {
 		named_g_tat_interval = atoi(option + 4);
 	} else {
-		fprintf(stderr, "unknown -T flag '%s\n", option);
+		fprintf(stderr, "unknown -T flag '%s'\n", option);
 	}
 }
 
@@ -1159,24 +1168,30 @@ setup(void) {
 	 */
 	if (clienttest)
 		ns_server_setoption(sctx, NS_SERVER_CLIENTTEST, true);
-	if (dropedns)
-		ns_server_setoption(sctx, NS_SERVER_DROPEDNS, true);
-	if (noedns)
-		ns_server_setoption(sctx, NS_SERVER_NOEDNS, true);
-	if (nosoa)
-		ns_server_setoption(sctx, NS_SERVER_NOSOA, true);
-	if (noaa)
-		ns_server_setoption(sctx, NS_SERVER_NOAA, true);
-	if (nonearest)
-		ns_server_setoption(sctx, NS_SERVER_NONEAREST, true);
-	if (notcp)
-		ns_server_setoption(sctx, NS_SERVER_NOTCP, true);
-	if (fixedlocal)
-		ns_server_setoption(sctx, NS_SERVER_FIXEDLOCAL, true);
 	if (disable4)
 		ns_server_setoption(sctx, NS_SERVER_DISABLE4, true);
 	if (disable6)
 		ns_server_setoption(sctx, NS_SERVER_DISABLE6, true);
+	if (dropedns)
+		ns_server_setoption(sctx, NS_SERVER_DROPEDNS, true);
+	if (ednsformerr)	/* STD13 server */
+		ns_server_setoption(sctx, NS_SERVER_EDNSFORMERR, true);
+	if (ednsnotimp)
+		ns_server_setoption(sctx, NS_SERVER_EDNSNOTIMP, true);
+	if (ednsrefused)
+		ns_server_setoption(sctx, NS_SERVER_EDNSREFUSED, true);
+	if (fixedlocal)
+		ns_server_setoption(sctx, NS_SERVER_FIXEDLOCAL, true);
+	if (noaa)
+		ns_server_setoption(sctx, NS_SERVER_NOAA, true);
+	if (noedns)
+		ns_server_setoption(sctx, NS_SERVER_NOEDNS, true);
+	if (nonearest)
+		ns_server_setoption(sctx, NS_SERVER_NONEAREST, true);
+	if (nosoa)
+		ns_server_setoption(sctx, NS_SERVER_NOSOA, true);
+	if (notcp)
+		ns_server_setoption(sctx, NS_SERVER_NOTCP, true);
 	if (sigvalinsecs)
 		ns_server_setoption(sctx, NS_SERVER_SIGVALINSECS, true);
 
diff --git a/lib/ns/client.c b/lib/ns/client.c
index 03975f6640..bcf022e1ee 100644
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@@ -2534,6 +2534,31 @@ ns__client_request(isc_task_t *task, isc_event_t *event) {
 	client->ecs.scope = 0;
 
 	if (opt != NULL) {
+		/*
+		 * Are returning FORMERR to all EDNS queries?
+		 * Simulate a STD13 compliant server.
+		 */
+		if ((client->sctx->options & NS_SERVER_EDNSFORMERR) != 0) {
+			ns_client_error(client, DNS_R_FORMERR);
+			return;
+		}
+
+		/*
+		 * Are returning NOTIMP to all EDNS queries?
+		 */
+		if ((client->sctx->options & NS_SERVER_EDNSNOTIMP) != 0) {
+			ns_client_error(client, DNS_R_NOTIMP);
+			return;
+		}
+
+		/*
+		 * Are returning REFUSED to all EDNS queries?
+		 */
+		if ((client->sctx->options & NS_SERVER_EDNSREFUSED) != 0) {
+			ns_client_error(client, DNS_R_REFUSED);
+			return;
+		}
+
 		/*
 		 * Are we dropping all EDNS queries?
 		 */
@@ -2541,6 +2566,7 @@ ns__client_request(isc_task_t *task, isc_event_t *event) {
 			ns_client_next(client, ISC_R_SUCCESS);
 			return;
 		}
+
 		result = process_opt(client, opt);
 		if (result != ISC_R_SUCCESS)
 			return;
diff --git a/lib/ns/include/ns/server.h b/lib/ns/include/ns/server.h
index a5ecf204c9..c4a0f71ecd 100644
--- a/lib/ns/include/ns/server.h
+++ b/lib/ns/include/ns/server.h
@@ -44,6 +44,9 @@
 #define NS_SERVER_DISABLE6	0x00000200U	/*%< -4 */
 #define NS_SERVER_FIXEDLOCAL	0x00000400U	/*%< -T fixedlocal */
 #define NS_SERVER_SIGVALINSECS	0x00000800U	/*%< -T sigvalinsecs */
+#define NS_SERVER_EDNSFORMERR	0x00001000U	/*%< -T ednsformerr (STD13) */
+#define NS_SERVER_EDNSNOTIMP	0x00002000U	/*%< -T ednsnotimp */
+#define NS_SERVER_EDNSREFUSED	0x00004000U	/*%< -T ednsrefused */
 
 /*%
  * Type for callback function to get hostname.