diff -up bind-9.7.3-P3/bin/nsupdate/nsupdate.c.rh714049 bind-9.7.3-P3/bin/nsupdate/nsupdate.c
--- bind-9.7.3-P3/bin/nsupdate/nsupdate.c.rh714049	2011-08-12 14:17:39.520175003 +0200
+++ bind-9.7.3-P3/bin/nsupdate/nsupdate.c	2011-08-12 15:11:01.812173573 +0200
@@ -109,6 +109,13 @@ extern int h_errno;
 
 #define DNSDEFAULTPORT 53
 
+/*
+ * Assume that bind9_getaddresses returns IPv6 and IPv4 addrs
+ * so when master server is not reachable via IPv6
+ * we can switch to IPv4.
+ */
+#define MAX_SERVERADDRS 4
+
 static isc_uint16_t dnsport = DNSDEFAULTPORT;
 
 #ifndef RESOLV_CONF
@@ -151,6 +158,8 @@ static isc_sockaddr_t *servers;
 static int ns_inuse = 0;
 static int ns_total = 0;
 static isc_sockaddr_t *userserver = NULL;
+static int curserver = 0;
+static int userservers = 0;
 static isc_sockaddr_t *localaddr = NULL;
 static isc_sockaddr_t *serveraddr = NULL;
 static isc_sockaddr_t tempaddr;
@@ -703,7 +712,8 @@ doshutdown(void) {
 	isc_task_detach(&global_task);
 
 	if (userserver != NULL)
-		isc_mem_put(mctx, userserver, sizeof(isc_sockaddr_t));
+		isc_mem_put(mctx, userserver,
+			    MAX_SERVERADDRS * sizeof(isc_sockaddr_t));
 
 	if (localaddr != NULL)
 		isc_mem_put(mctx, localaddr, sizeof(isc_sockaddr_t));
@@ -914,17 +924,21 @@ setup_system(void) {
 }
 
 static void
-get_address(char *host, in_port_t port, isc_sockaddr_t *sockaddr) {
+get_addresses(char *host, in_port_t port, isc_sockaddr_t *sockaddr, int *naddrs) {
 	int count;
 	isc_result_t result;
 
 	isc_app_block();
-	result = bind9_getaddresses(host, port, sockaddr, 1, &count);
+	result = bind9_getaddresses(host, port, sockaddr,
+				    (naddrs == NULL) ? 1 : MAX_SERVERADDRS, &count);
 	isc_app_unblock();
 	if (result != ISC_R_SUCCESS)
 		fatal("couldn't get address for '%s': %s",
 		      host, isc_result_totext(result));
-	INSIST(count == 1);
+	if (naddrs == NULL)
+		INSIST(count == 1);
+	else
+		*naddrs = count;
 }
 
 #define PARSE_ARGS_FMT "dDML:y:ghlovk:p:rR::t:u:"
@@ -1364,12 +1378,14 @@ evaluate_server(char *cmdline) {
 	}
 
 	if (userserver == NULL) {
-		userserver = isc_mem_get(mctx, sizeof(isc_sockaddr_t));
+		userserver = isc_mem_get(mctx,
+					 MAX_SERVERADDRS * sizeof(isc_sockaddr_t));
 		if (userserver == NULL)
 			fatal("out of memory");
 	}
 
-	get_address(server, (in_port_t)port, userserver);
+	memset(userserver, 0, MAX_SERVERADDRS * sizeof(isc_sockaddr_t));
+	get_addresses(server, (in_port_t)port, userserver, &userservers);
 
 	return (STATUS_MORE);
 }
@@ -2207,19 +2223,25 @@ recvsoa(isc_task_t *task, isc_event_t *e
 
 	if (eresult != ISC_R_SUCCESS) {
 		char addrbuf[ISC_SOCKADDR_FORMATSIZE];
+		isc_sockaddr_t *server;
 
 		isc_sockaddr_format(addr, addrbuf, sizeof(addrbuf));
 		fprintf(stderr, "; Communication with %s failed: %s\n",
 			addrbuf, isc_result_totext(eresult));
-		if (userserver != NULL)
-			fatal("could not talk to specified name server");
-		else if (++ns_inuse >= lwconf->nsnext)
+		if (userserver != NULL) {
+			if (++curserver == MAX_SERVERADDRS)
+				fatal("could not talk to specified name server");
+			else
+				ddebug("recvsoa: trying next server");
+		} else if (++ns_inuse >= lwconf->nsnext)
 			fatal("could not talk to any default name server");
 		ddebug("Destroying request [%p]", request);
 		dns_request_destroy(&request);
 		dns_message_renderreset(soaquery);
 		dns_message_settsigkey(soaquery, NULL);
-		sendrequest(localaddr, &servers[ns_inuse], soaquery, &request);
+		server = (userserver != NULL) ? &userserver[curserver] :
+						&servers[ns_inuse];
+		sendrequest(localaddr, server, soaquery, &request);
 		isc_mem_put(mctx, reqinfo, sizeof(nsu_requestinfo_t));
 		isc_event_free(&event);
 		setzoneclass(dns_rdataclass_none);
@@ -2351,7 +2373,7 @@ recvsoa(isc_task_t *task, isc_event_t *e
 	}
 
 	if (userserver != NULL)
-		serveraddr = userserver;
+		serveraddr = &userserver[curserver];
 	else {
 		char serverstr[DNS_NAME_MAXTEXT+1];
 		isc_buffer_t buf;
@@ -2360,7 +2382,7 @@ recvsoa(isc_task_t *task, isc_event_t *e
 		result = dns_name_totext(&master, ISC_TRUE, &buf);
 		check_result(result, "dns_name_totext");
 		serverstr[isc_buffer_usedlength(&buf)] = 0;
-		get_address(serverstr, dnsport, &tempaddr);
+		get_addresses(serverstr, dnsport, &tempaddr, NULL);
 		serveraddr = &tempaddr;
 	}
 	dns_rdata_freestruct(&soa);
@@ -2464,9 +2486,9 @@ start_gssrequest(dns_name_t *master)
 			fatal("out of memory");
 	}
 	if (userserver == NULL)
-		get_address(namestr, dnsport, kserver);
+		get_addresses(namestr, dnsport, kserver, NULL);
 	else
-		(void)memcpy(kserver, userserver, sizeof(isc_sockaddr_t));
+		(void)memcpy(kserver, &userserver[curserver], sizeof(isc_sockaddr_t));
 
 	dns_fixedname_init(&fname);
 	servname = dns_fixedname_name(&fname);
@@ -2594,15 +2616,17 @@ recvgss(isc_task_t *task, isc_event_t *e
 		isc_sockaddr_format(addr, addrbuf, sizeof(addrbuf));
 		fprintf(stderr, "; Communication with %s failed: %s\n",
 			addrbuf, isc_result_totext(eresult));
-		if (userserver != NULL)
+		if (userserver != NULL) {
 			fatal("could not talk to specified name server");
-		else if (++ns_inuse >= lwconf->nsnext)
+		} else if (++ns_inuse >= lwconf->nsnext)
 			fatal("could not talk to any default name server");
 		ddebug("Destroying request [%p]", request);
 		dns_request_destroy(&request);
 		dns_message_renderreset(tsigquery);
-		sendrequest(localaddr, &servers[ns_inuse], tsigquery,
-			    &request);
+		sendrequest(localaddr,
+			    (userserver != NULL) ? &userserver[curserver] :
+						   &servers[ns_inuse],
+			    tsigquery, &request);
 		isc_mem_put(mctx, reqinfo, sizeof(nsu_gssinfo_t));
 		isc_event_free(&event);
 		return;