diff --git a/CHANGES b/CHANGES
index fecd972a24..e21134250f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+3225.	[bug]		Silence spurious "setsockopt(517, IPV6_V6ONLY) failed"
+			messages. [RT #26507]
+
 3224.	[bug]		'rndc signing' argument parsing was broken. [RT #26684]
 
 3223.	[bug]		'task_test privilege_drop' generated false positives.
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index ab049fa3c1..cf58cf9319 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: dispatch.c,v 1.174 2011/07/28 23:47:58 tbox Exp $ */
+/* $Id: dispatch.c,v 1.175 2011/11/29 01:03:47 marka Exp $ */
 
 /*! \file */
 
@@ -1810,6 +1810,10 @@ open_socket(isc_socketmgr_t *mgr, isc_sockaddr_t *local,
 		result = isc_socket_dup(dup_socket, &sock);
 		if (result != ISC_R_SUCCESS)
 			return (result);
+
+		isc_socket_setname(sock, "dispatcher", NULL);
+		*sockp = sock;
+		return (ISC_R_SUCCESS);
 	} else {
 		result = isc_socket_create(mgr, isc_sockaddr_pf(local),
 					isc_sockettype_udp, &sock);
diff --git a/lib/isc/tests/socket_test.c b/lib/isc/tests/socket_test.c
index 501a3b8c4e..4245ecb0db 100644
--- a/lib/isc/tests/socket_test.c
+++ b/lib/isc/tests/socket_test.c
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket_test.c,v 1.4 2011/09/02 21:15:38 each Exp $ */
+/* $Id: socket_test.c,v 1.5 2011/11/29 01:03:47 marka Exp $ */
 
 /*! \file */
 
@@ -181,12 +181,10 @@ ATF_TC_BODY(udp_dup, tc) {
 
 	result = isc_socket_create(socketmgr, PF_INET, isc_sockettype_udp, &s2);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
-	result = isc_socket_dup(s2, &s3);
-	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
-
 	result = isc_socket_bind(s2, &addr2, ISC_SOCKET_REUSEADDRESS);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
-	result = isc_socket_bind(s3, &addr2, ISC_SOCKET_REUSEADDRESS);
+
+	result = isc_socket_dup(s2, &s3);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
 
 	result = isc_task_create(taskmgr, 0, &task);
@@ -245,7 +243,6 @@ ATF_TC_BODY(udp_dup, tc) {
 	isc_test_end();
 }
 
-
 /*
  * Main
  */
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 2512533f1b..f20f3d31ff 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.c,v 1.348 2011/08/25 11:37:13 marka Exp $ */
+/* $Id: socket.c,v 1.349 2011/11/29 01:03:47 marka Exp $ */
 
 /*! \file */
 
@@ -2270,6 +2270,7 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock,
 	} else {
 		sock->fd = dup(dup_socket->fd);
 		sock->dupped = 1;
+		sock->bound = dup_socket->bound;
 	}
 	if (sock->fd == -1 && errno == EINTR && tries++ < 42)
 		goto again;
@@ -5028,54 +5029,55 @@ isc__socket_bind(isc_socket_t *sock0, isc_sockaddr_t *sockaddr,
 	LOCK(&sock->lock);
 
 	INSIST(!sock->bound);
+	INSIST(!sock->dupped);
 
 	if (sock->pf != sockaddr->type.sa.sa_family) {
 		UNLOCK(&sock->lock);
 		return (ISC_R_FAMILYMISMATCH);
 	}
-	if (!sock->dupped) {
-		/*
-		 * Only set SO_REUSEADDR when we want a specific port.
-		 */
-#ifdef AF_UNIX
-		if (sock->pf == AF_UNIX)
-			goto bind_socket;
-#endif
-		if ((options & ISC_SOCKET_REUSEADDRESS) != 0 &&
-		    isc_sockaddr_getport(sockaddr) != (in_port_t)0 &&
-		    setsockopt(sock->fd, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
-			       sizeof(on)) < 0) {
-			UNEXPECTED_ERROR(__FILE__, __LINE__,
-					 "setsockopt(%d) %s", sock->fd,
-					 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
-							ISC_MSG_FAILED, "failed"));
-			/* Press on... */
-		}
-#ifdef AF_UNIX
-	 bind_socket:
-#endif
-		if (bind(sock->fd, &sockaddr->type.sa, sockaddr->length) < 0) {
-			inc_stats(sock->manager->stats,
-				  sock->statsindex[STATID_BINDFAIL]);
 
-			UNLOCK(&sock->lock);
-			switch (errno) {
-			case EACCES:
-				return (ISC_R_NOPERM);
-			case EADDRNOTAVAIL:
-				return (ISC_R_ADDRNOTAVAIL);
-			case EADDRINUSE:
-				return (ISC_R_ADDRINUSE);
-			case EINVAL:
-				return (ISC_R_BOUND);
-			default:
-				isc__strerror(errno, strbuf, sizeof(strbuf));
-				UNEXPECTED_ERROR(__FILE__, __LINE__, "bind: %s",
-						 strbuf);
-				return (ISC_R_UNEXPECTED);
-			}
+	/*
+	 * Only set SO_REUSEADDR when we want a specific port.
+	 */
+#ifdef AF_UNIX
+	if (sock->pf == AF_UNIX)
+		goto bind_socket;
+#endif
+	if ((options & ISC_SOCKET_REUSEADDRESS) != 0 &&
+	    isc_sockaddr_getport(sockaddr) != (in_port_t)0 &&
+	    setsockopt(sock->fd, SOL_SOCKET, SO_REUSEADDR, (void *)&on,
+		       sizeof(on)) < 0) {
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+				 "setsockopt(%d) %s", sock->fd,
+				 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
+						ISC_MSG_FAILED, "failed"));
+		/* Press on... */
+	}
+#ifdef AF_UNIX
+ bind_socket:
+#endif
+	if (bind(sock->fd, &sockaddr->type.sa, sockaddr->length) < 0) {
+		inc_stats(sock->manager->stats,
+			  sock->statsindex[STATID_BINDFAIL]);
+
+		UNLOCK(&sock->lock);
+		switch (errno) {
+		case EACCES:
+			return (ISC_R_NOPERM);
+		case EADDRNOTAVAIL:
+			return (ISC_R_ADDRNOTAVAIL);
+		case EADDRINUSE:
+			return (ISC_R_ADDRINUSE);
+		case EINVAL:
+			return (ISC_R_BOUND);
+		default:
+			isc__strerror(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__, "bind: %s",
+					 strbuf);
+			return (ISC_R_UNEXPECTED);
 		}
 	}
+
 	socket_log(sock, sockaddr, TRACE,
 		   isc_msgcat, ISC_MSGSET_SOCKET, ISC_MSG_BOUND, "bound");
 	sock->bound = 1;
@@ -5718,6 +5720,7 @@ isc__socket_ipv6only(isc_socket_t *sock0, isc_boolean_t yes) {
 #endif
 
 	REQUIRE(VALID_SOCKET(sock));
+	INSIST(!sock->dupped);
 
 #ifdef IPV6_V6ONLY
 	if (sock->pf == AF_INET6) {
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index 953a81119e..8bb5b3273b 100644
--- a/lib/isc/win32/socket.c
+++ b/lib/isc/win32/socket.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.c,v 1.92 2011/08/23 18:24:33 each Exp $ */
+/* $Id: socket.c,v 1.93 2011/11/29 01:03:47 marka Exp $ */
 
 /* This code uses functions which are only available on Server 2003 and
  * higher, and Windows XP and higher.
@@ -1688,6 +1688,7 @@ socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
 		 */
 		sock->fd = _dup(dup_socket->fd);
 		sock->dupped = 1;
+		sock->bound = dup_socket->bound;
 	}
 
 	if (sock->fd == INVALID_SOCKET) {
@@ -3175,6 +3176,7 @@ isc__socket_bind(isc_socket_t *sock, isc_sockaddr_t *sockaddr,
 	}
 
 	INSIST(!sock->bound);
+	INSIST(!sock->dupped);
 
 	if (sock->pf != sockaddr->type.sa.sa_family) {
 		UNLOCK(&sock->lock);