diff --git a/CHANGES b/CHANGES
index b26c348341..4baa0b628a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,8 @@
+3137.	[func]		Improve hardware scalability by allowing multiple
+			worker threads to process incoming UDP packets.
+			This can significantly increase query throughput
+			on some systems.  [RT #22992]
+
 3136.	[func]		Add RFC 1918 reverse zones to the list of built-in 
 			empty zones switched on by the 'empty-zones-enable'
 			option. [RT #24990]
diff --git a/bin/named/client.c b/bin/named/client.c
index 6e8ddd1b51..0e26afa7c2 100644
--- a/bin/named/client.c
+++ b/bin/named/client.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: client.c,v 1.273 2011/05/05 23:44:52 marka Exp $ */
+/* $Id: client.c,v 1.274 2011/07/28 04:04:36 each Exp $ */
 
 #include <config.h>
 
@@ -2530,8 +2530,10 @@ ns_clientmgr_createclients(ns_clientmgr_t *manager, unsigned int n,
 			   ns_interface_t *ifp, isc_boolean_t tcp)
 {
 	isc_result_t result = ISC_R_SUCCESS;
+	isc_boolean_t success = ISC_FALSE;
 	unsigned int i;
 	ns_client_t *client;
+	unsigned int disp;
 
 	REQUIRE(VALID_MANAGER(manager));
 	REQUIRE(n > 0);
@@ -2546,61 +2548,68 @@ ns_clientmgr_createclients(ns_clientmgr_t *manager, unsigned int n,
 
 	LOCK(&manager->lock);
 
-	for (i = 0; i < n; i++) {
-		isc_event_t *ev;
-		/*
-		 * Allocate a client.  First try to get a recycled one;
-		 * if that fails, make a new one.
-		 */
-		client = NULL;
-		if (!ns_g_clienttest)
-			client = ISC_LIST_HEAD(manager->inactive);
-		if (client != NULL) {
-			MTRACE("recycle");
-			ISC_LIST_UNLINK(manager->inactive, client, link);
-			client->list = NULL;
-		} else {
-			MTRACE("create new");
-			result = client_create(manager, &client);
-			if (result != ISC_R_SUCCESS)
-				break;
+	for (disp = 0; disp < n; disp++) {
+		for (i = 0; i < n; i++) {
+			isc_event_t *ev;
+
+			/*
+			 * Allocate a client.  First try to get a recycled one;
+			 * if that fails, make a new one.
+			 */
+			client = NULL;
+			if (!ns_g_clienttest)
+				client = ISC_LIST_HEAD(manager->inactive);
+			if (client != NULL) {
+				MTRACE("recycle");
+				ISC_LIST_UNLINK(manager->inactive, client,
+					        link);
+				client->list = NULL;
+			} else {
+				MTRACE("create new");
+				result = client_create(manager, &client);
+				if (result != ISC_R_SUCCESS)
+					break;
+			}
+
+			ns_interface_attach(ifp, &client->interface);
+			client->state = NS_CLIENTSTATE_READY;
+			INSIST(client->recursionquota == NULL);
+
+			if (tcp) {
+				client->attributes |= NS_CLIENTATTR_TCP;
+				isc_socket_attach(ifp->tcpsocket,
+						  &client->tcplistener);
+			} else {
+				isc_socket_t *sock;
+
+				dns_dispatch_attach(ifp->udpdispatch[disp],
+						    &client->dispatch);
+				sock = dns_dispatch_getsocket(client->dispatch);
+				isc_socket_attach(sock, &client->udpsocket);
+			}
+
+			client->manager = manager;
+			ISC_LIST_APPEND(manager->active, client, link);
+			client->list = &manager->active;
+
+			INSIST(client->nctls == 0);
+			client->nctls++;
+			ev = &client->ctlevent;
+			isc_task_send(client->task, &ev);
+
+			success = ISC_TRUE;
 		}
-
-		ns_interface_attach(ifp, &client->interface);
-		client->state = NS_CLIENTSTATE_READY;
-		INSIST(client->recursionquota == NULL);
-
-		if (tcp) {
-			client->attributes |= NS_CLIENTATTR_TCP;
-			isc_socket_attach(ifp->tcpsocket,
-					  &client->tcplistener);
-		} else {
-			isc_socket_t *sock;
-
-			dns_dispatch_attach(ifp->udpdispatch,
-					    &client->dispatch);
-			sock = dns_dispatch_getsocket(client->dispatch);
-			isc_socket_attach(sock, &client->udpsocket);
-		}
-		client->manager = manager;
-		ISC_LIST_APPEND(manager->active, client, link);
-		client->list = &manager->active;
-
-		INSIST(client->nctls == 0);
-		client->nctls++;
-		ev = &client->ctlevent;
-		isc_task_send(client->task, &ev);
-	}
-	if (i != 0) {
-		/*
-		 * We managed to create at least one client, so we
-		 * declare victory.
-		 */
-		result = ISC_R_SUCCESS;
 	}
 
 	UNLOCK(&manager->lock);
 
+	/*
+	 * If managed to create at least one client for
+	 * one dispatch, we declare victory.
+	 */
+	if (success)
+		return (ISC_R_SUCCESS);
+
 	return (result);
 }
 
diff --git a/bin/named/include/named/interfacemgr.h b/bin/named/include/named/interfacemgr.h
index 2724c393cd..2821984cc8 100644
--- a/bin/named/include/named/interfacemgr.h
+++ b/bin/named/include/named/interfacemgr.h
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: interfacemgr.h,v 1.33 2007/06/19 23:46:59 tbox Exp $ */
+/* $Id: interfacemgr.h,v 1.34 2011/07/28 04:04:36 each Exp $ */
 
 #ifndef NAMED_INTERFACEMGR_H
 #define NAMED_INTERFACEMGR_H 1
@@ -65,7 +65,8 @@
 #define NS_INTERFACE_VALID(t)	ISC_MAGIC_VALID(t, IFACE_MAGIC)
 
 #define NS_INTERFACEFLAG_ANYADDR	0x01U	/*%< bound to "any" address */
-
+#define MAX_UDP_DISPATCH 128		/*%< Maximum number of UDP dispatchers
+                                                     to start per interface */
 /*% The nameserver interface structure */
 struct ns_interface {
 	unsigned int		magic;		/*%< Magic number. */
@@ -76,11 +77,13 @@ struct ns_interface {
 	isc_sockaddr_t		addr;           /*%< Address and port. */
 	unsigned int		flags;		/*%< Interface characteristics */
 	char 			name[32];	/*%< Null terminated. */
-	dns_dispatch_t *	udpdispatch;	/*%< UDP dispatcher. */
+	dns_dispatch_t *	udpdispatch[MAX_UDP_DISPATCH];
+						/*%< UDP dispatchers. */
 	isc_socket_t *		tcpsocket;	/*%< TCP socket. */
 	int			ntcptarget;	/*%< Desired number of concurrent
 						     TCP accepts */
 	int			ntcpcurrent;	/*%< Current ditto, locked */
+	int			nudpdispatch;	/*%< Number of UDP dispatches */
 	ns_clientmgr_t *	clientmgr;	/*%< Client manager. */
 	ISC_LINK(ns_interface_t) link;
 };
diff --git a/bin/named/interfacemgr.c b/bin/named/interfacemgr.c
index 782aacd52e..7149604039 100644
--- a/bin/named/interfacemgr.c
+++ b/bin/named/interfacemgr.c
@@ -15,13 +15,14 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: interfacemgr.c,v 1.97 2011/03/12 04:59:46 tbox Exp $ */
+/* $Id: interfacemgr.c,v 1.98 2011/07/28 04:04:36 each Exp $ */
 
 /*! \file */
 
 #include <config.h>
 
 #include <isc/interfaceiter.h>
+#include <isc/os.h>
 #include <isc/string.h>
 #include <isc/task.h>
 #include <isc/util.h>
@@ -195,6 +196,7 @@ ns_interface_create(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr,
 	strncpy(ifp->name, name, sizeof(ifp->name));
 	ifp->name[sizeof(ifp->name)-1] = '\0';
 	ifp->clientmgr = NULL;
+	int disp;
 
 	result = isc_mutex_init(&ifp->lock);
 	if (result != ISC_R_SUCCESS)
@@ -210,7 +212,8 @@ ns_interface_create(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr,
 		goto clientmgr_create_failure;
 	}
 
-	ifp->udpdispatch = NULL;
+	for (disp = 0; disp < MAX_UDP_DISPATCH; disp++)
+		ifp->udpdispatch[disp] = NULL;
 
 	ifp->tcpsocket = NULL;
 	/*
@@ -221,6 +224,7 @@ ns_interface_create(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr,
 	 */
 	ifp->ntcptarget = 1;
 	ifp->ntcpcurrent = 0;
+	ifp->nudpdispatch = 0;
 
 	ISC_LINK_INIT(ifp, link);
 
@@ -247,6 +251,7 @@ ns_interface_listenudp(ns_interface_t *ifp) {
 	isc_result_t result;
 	unsigned int attrs;
 	unsigned int attrmask;
+	int disp, i;
 
 	attrs = 0;
 	attrs |= DNS_DISPATCHATTR_UDP;
@@ -258,15 +263,25 @@ ns_interface_listenudp(ns_interface_t *ifp) {
 	attrmask = 0;
 	attrmask |= DNS_DISPATCHATTR_UDP | DNS_DISPATCHATTR_TCP;
 	attrmask |= DNS_DISPATCHATTR_IPV4 | DNS_DISPATCHATTR_IPV6;
-	result = dns_dispatch_getudp(ifp->mgr->dispatchmgr, ns_g_socketmgr,
-				     ns_g_taskmgr, &ifp->addr,
-				     4096, 1000, 32768, 8219, 8237,
-				     attrs, attrmask, &ifp->udpdispatch);
-	if (result != ISC_R_SUCCESS) {
-		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
-			      "could not listen on UDP socket: %s",
-			      isc_result_totext(result));
-		goto udp_dispatch_failure;
+
+	ifp->nudpdispatch = ISC_MIN(isc_os_ncpus(), MAX_UDP_DISPATCH);
+	for (disp = 0; disp < ifp->nudpdispatch; disp++) {
+		result = dns_dispatch_getudp_dup(ifp->mgr->dispatchmgr,
+						 ns_g_socketmgr,
+						 ns_g_taskmgr, &ifp->addr,
+						 4096, 1000, 32768, 8219, 8237,
+						 attrs, attrmask,
+						 &ifp->udpdispatch[disp],
+						 disp == 0
+						    ? NULL
+						    : ifp->udpdispatch[0]);
+		if (result != ISC_R_SUCCESS) {
+			isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
+				      "could not listen on UDP socket: %s",
+				      isc_result_totext(result));
+			goto udp_dispatch_failure;
+		}
+
 	}
 
 	result = ns_clientmgr_createclients(ifp->clientmgr, ns_g_cpus,
@@ -277,12 +292,17 @@ ns_interface_listenudp(ns_interface_t *ifp) {
 				 isc_result_totext(result));
 		goto addtodispatch_failure;
 	}
+
 	return (ISC_R_SUCCESS);
 
  addtodispatch_failure:
-	dns_dispatch_changeattributes(ifp->udpdispatch, 0,
-				      DNS_DISPATCHATTR_NOLISTEN);
-	dns_dispatch_detach(&ifp->udpdispatch);
+	for (i = disp - 1; i <= 0; i--) {
+		dns_dispatch_changeattributes(ifp->udpdispatch[i], 0,
+					      DNS_DISPATCHATTR_NOLISTEN);
+		dns_dispatch_detach(&(ifp->udpdispatch[i]));
+	}
+	ifp->nudpdispatch = 0;
+
  udp_dispatch_failure:
 	return (result);
 }
@@ -397,14 +417,16 @@ static void
 ns_interface_destroy(ns_interface_t *ifp) {
 	isc_mem_t *mctx = ifp->mgr->mctx;
 	REQUIRE(NS_INTERFACE_VALID(ifp));
+	int disp;
 
 	ns_interface_shutdown(ifp);
 
-	if (ifp->udpdispatch != NULL) {
-		dns_dispatch_changeattributes(ifp->udpdispatch, 0,
-					      DNS_DISPATCHATTR_NOLISTEN);
-		dns_dispatch_detach(&ifp->udpdispatch);
-	}
+	for (disp = ifp->nudpdispatch; disp >= 0; disp--)
+		if (ifp->udpdispatch[disp] != NULL) {
+			dns_dispatch_changeattributes(ifp->udpdispatch[disp], 0,
+						    DNS_DISPATCHATTR_NOLISTEN);
+			dns_dispatch_detach(&(ifp->udpdispatch[disp]));
+		}
 	if (ifp->tcpsocket != NULL)
 		isc_socket_detach(&ifp->tcpsocket);
 
diff --git a/configure.in b/configure.in
index 6d55410e87..9a9f3e4858 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(1)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl
 
-AC_REVISION($Revision: 1.528 $)
+AC_REVISION($Revision: 1.529 $)
 
 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.59)
@@ -2552,7 +2552,7 @@ yes)
 esac
 AC_SUBST(ISC_PLATFORM_HAVEIFNAMETOINDEX)
 
-AC_CHECK_FUNCS(nanosleep)
+AC_CHECK_FUNCS(nanosleep usleep)
 
 #
 # Machine architecture dependent features
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 1e5f415b44..ba3eefe013 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: dispatch.c,v 1.172 2011/04/06 10:27:16 marka Exp $ */
+/* $Id: dispatch.c,v 1.173 2011/07/28 04:04:36 each Exp $ */
 
 /*! \file */
 
@@ -312,14 +312,16 @@ static isc_result_t get_udpsocket(dns_dispatchmgr_t *mgr,
 				  dns_dispatch_t *disp,
 				  isc_socketmgr_t *sockmgr,
 				  isc_sockaddr_t *localaddr,
-				  isc_socket_t **sockp);
+				  isc_socket_t **sockp,
+				  isc_socket_t *dup_socket);
 static isc_result_t dispatch_createudp(dns_dispatchmgr_t *mgr,
 				       isc_socketmgr_t *sockmgr,
 				       isc_taskmgr_t *taskmgr,
 				       isc_sockaddr_t *localaddr,
 				       unsigned int maxrequests,
 				       unsigned int attributes,
-				       dns_dispatch_t **dispp);
+				       dns_dispatch_t **dispp,
+				       isc_socket_t *dup_socket);
 static isc_boolean_t destroy_mgr_ok(dns_dispatchmgr_t *mgr);
 static void destroy_mgr(dns_dispatchmgr_t **mgrp);
 static isc_result_t qid_allocate(dns_dispatchmgr_t *mgr, unsigned int buckets,
@@ -327,7 +329,8 @@ static isc_result_t qid_allocate(dns_dispatchmgr_t *mgr, unsigned int buckets,
 				 isc_boolean_t needaddrtable);
 static void qid_destroy(isc_mem_t *mctx, dns_qid_t **qidp);
 static isc_result_t open_socket(isc_socketmgr_t *mgr, isc_sockaddr_t *local,
-				unsigned int options, isc_socket_t **sockp);
+				unsigned int options, isc_socket_t **sockp,
+				isc_socket_t *dup_socket);
 static isc_boolean_t portavailable(dns_dispatchmgr_t *mgr, isc_socket_t *sock,
 				   isc_sockaddr_t *sockaddrp);
 
@@ -902,7 +905,8 @@ get_dispsocket(dns_dispatch_t *disp, isc_sockaddr_t *dest,
 		portentry = port_search(disp, port);
 		if (portentry != NULL)
 			bindoptions |= ISC_SOCKET_REUSEADDRESS;
-		result = open_socket(sockmgr, &localaddr, bindoptions, &sock);
+		result = open_socket(sockmgr, &localaddr, bindoptions, &sock,
+			             NULL);
 		if (result == ISC_R_SUCCESS) {
 			if (portentry == NULL) {
 				portentry = new_portentry(disp, port);
@@ -1787,19 +1791,14 @@ destroy_mgr(dns_dispatchmgr_t **mgrp) {
 
 static isc_result_t
 open_socket(isc_socketmgr_t *mgr, isc_sockaddr_t *local,
-	    unsigned int options, isc_socket_t **sockp)
+	    unsigned int options, isc_socket_t **sockp,
+	    isc_socket_t *dup_socket)
 {
 	isc_socket_t *sock;
 	isc_result_t result;
 
 	sock = *sockp;
-	if (sock == NULL) {
-		result = isc_socket_create(mgr, isc_sockaddr_pf(local),
-					   isc_sockettype_udp, &sock);
-		if (result != ISC_R_SUCCESS)
-			return (result);
-		isc_socket_setname(sock, "dispatcher", NULL);
-	} else {
+	if (sock != NULL) {
 #ifdef BIND9
 		result = isc_socket_open(sock);
 		if (result != ISC_R_SUCCESS)
@@ -1807,8 +1806,19 @@ open_socket(isc_socketmgr_t *mgr, isc_sockaddr_t *local,
 #else
 		INSIST(0);
 #endif
+	} else if (dup_socket != NULL) {
+		result = isc_socket_dup(dup_socket, &sock);
+		if (result != ISC_R_SUCCESS)
+			return (result);
+	} else {
+		result = isc_socket_create(mgr, isc_sockaddr_pf(local),
+					isc_sockettype_udp, &sock);
+		if (result != ISC_R_SUCCESS)
+			return (result);
 	}
 
+	isc_socket_setname(sock, "dispatcher", NULL);
+
 #ifndef ISC_ALLOW_MAPPED
 	isc_socket_ipv6only(sock, ISC_TRUE);
 #endif
@@ -2646,13 +2656,13 @@ dns_dispatch_createtcp(dns_dispatchmgr_t *mgr, isc_socket_t *sock,
 }
 
 isc_result_t
-dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
+dns_dispatch_getudp_dup(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		    isc_taskmgr_t *taskmgr, isc_sockaddr_t *localaddr,
 		    unsigned int buffersize,
 		    unsigned int maxbuffers, unsigned int maxrequests,
 		    unsigned int buckets, unsigned int increment,
 		    unsigned int attributes, unsigned int mask,
-		    dns_dispatch_t **dispp)
+		    dns_dispatch_t **dispp, dns_dispatch_t *dup_dispatch)
 {
 	isc_result_t result;
 	dns_dispatch_t *disp = NULL;
@@ -2683,28 +2693,31 @@ dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 	/*
 	 * See if we have a dispatcher that matches.
 	 */
-	result = dispatch_find(mgr, localaddr, attributes, mask, &disp);
-	if (result == ISC_R_SUCCESS) {
-		disp->refcount++;
+	if (dup_dispatch == NULL) {
+		result = dispatch_find(mgr, localaddr, attributes, mask, &disp);
+		if (result == ISC_R_SUCCESS) {
+			disp->refcount++;
 
-		if (disp->maxrequests < maxrequests)
-			disp->maxrequests = maxrequests;
+			if (disp->maxrequests < maxrequests)
+				disp->maxrequests = maxrequests;
 
-		if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) == 0 &&
-		    (attributes & DNS_DISPATCHATTR_NOLISTEN) != 0)
-		{
-			disp->attributes |= DNS_DISPATCHATTR_NOLISTEN;
-			if (disp->recv_pending != 0)
-				isc_socket_cancel(disp->socket, disp->task[0],
-						  ISC_SOCKCANCEL_RECV);
+			if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) == 0
+			    && (attributes & DNS_DISPATCHATTR_NOLISTEN) != 0)
+			{
+				disp->attributes |= DNS_DISPATCHATTR_NOLISTEN;
+				if (disp->recv_pending != 0)
+					isc_socket_cancel(disp->socket,
+						          disp->task[0],
+							  ISC_SOCKCANCEL_RECV);
+			}
+
+			UNLOCK(&disp->lock);
+			UNLOCK(&mgr->lock);
+
+			*dispp = disp;
+
+			return (ISC_R_SUCCESS);
 		}
-
-		UNLOCK(&disp->lock);
-		UNLOCK(&mgr->lock);
-
-		*dispp = disp;
-
-		return (ISC_R_SUCCESS);
 	}
 
  createudp:
@@ -2712,7 +2725,11 @@ dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 	 * Nope, create one.
 	 */
 	result = dispatch_createudp(mgr, sockmgr, taskmgr, localaddr,
-				    maxrequests, attributes, &disp);
+				    maxrequests, attributes, &disp,
+				    dup_dispatch == NULL
+					    ? NULL
+					    : dup_dispatch->socket);
+
 	if (result != ISC_R_SUCCESS) {
 		UNLOCK(&mgr->lock);
 		return (result);
@@ -2720,9 +2737,24 @@ dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 
 	UNLOCK(&mgr->lock);
 	*dispp = disp;
+
 	return (ISC_R_SUCCESS);
 }
 
+isc_result_t
+dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
+		    isc_taskmgr_t *taskmgr, isc_sockaddr_t *localaddr,
+		    unsigned int buffersize,
+		    unsigned int maxbuffers, unsigned int maxrequests,
+		    unsigned int buckets, unsigned int increment,
+		    unsigned int attributes, unsigned int mask,
+		    dns_dispatch_t **dispp)
+{
+	return dns_dispatch_getudp_dup(mgr, sockmgr, taskmgr, localaddr,
+		    buffersize, maxbuffers, maxrequests, buckets, increment,
+		    attributes, mask, dispp, NULL);
+}
+
 /*
  * mgr should be locked.
  */
@@ -2734,7 +2766,7 @@ dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 static isc_result_t
 get_udpsocket(dns_dispatchmgr_t *mgr, dns_dispatch_t *disp,
 	      isc_socketmgr_t *sockmgr, isc_sockaddr_t *localaddr,
-	      isc_socket_t **sockp)
+	      isc_socket_t **sockp, isc_socket_t *dup_socket)
 {
 	unsigned int i, j;
 	isc_socket_t *held[DNS_DISPATCH_HELD];
@@ -2774,7 +2806,7 @@ get_udpsocket(dns_dispatchmgr_t *mgr, dns_dispatch_t *disp,
 					nports)];
 			isc_sockaddr_setport(&localaddr_bound, prt);
 			result = open_socket(sockmgr, &localaddr_bound,
-					     0, &sock);
+					     0, &sock, NULL);
 			if (result == ISC_R_SUCCESS ||
 			    result != ISC_R_ADDRINUSE) {
 				disp->localport = prt;
@@ -2790,7 +2822,8 @@ get_udpsocket(dns_dispatchmgr_t *mgr, dns_dispatch_t *disp,
 	} else {
 		/* Allow to reuse address for non-random ports. */
 		result = open_socket(sockmgr, localaddr,
-				     ISC_SOCKET_REUSEADDRESS, &sock);
+				     ISC_SOCKET_REUSEADDRESS, &sock,
+				     dup_socket);
 
 		if (result == ISC_R_SUCCESS)
 			*sockp = sock;
@@ -2802,7 +2835,7 @@ get_udpsocket(dns_dispatchmgr_t *mgr, dns_dispatch_t *disp,
 	i = 0;
 
 	for (j = 0; j < 0xffffU; j++) {
-		result = open_socket(sockmgr, localaddr, 0, &sock);
+		result = open_socket(sockmgr, localaddr, 0, &sock, NULL);
 		if (result != ISC_R_SUCCESS)
 			goto end;
 		else if (!anyport)
@@ -2841,7 +2874,8 @@ dispatch_createudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		   isc_sockaddr_t *localaddr,
 		   unsigned int maxrequests,
 		   unsigned int attributes,
-		   dns_dispatch_t **dispp)
+		   dns_dispatch_t **dispp,
+		   isc_socket_t *dup_socket)
 {
 	isc_result_t result;
 	dns_dispatch_t *disp;
@@ -2857,9 +2891,21 @@ dispatch_createudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		return (result);
 
 	if ((attributes & DNS_DISPATCHATTR_EXCLUSIVE) == 0) {
-		result = get_udpsocket(mgr, disp, sockmgr, localaddr, &sock);
+		result = get_udpsocket(mgr, disp, sockmgr, localaddr, &sock,
+				       dup_socket);
 		if (result != ISC_R_SUCCESS)
 			goto deallocate_dispatch;
+
+		if (isc_log_wouldlog(dns_lctx, 90)) {
+			char addrbuf[ISC_SOCKADDR_FORMATSIZE];
+
+			isc_sockaddr_format(localaddr, addrbuf,
+					    ISC_SOCKADDR_FORMATSIZE);
+			mgr_log(mgr, LVL(90), "dns_dispatch_createudp: Created"
+				" UDP dispatch for %s with socket fd %d\n",
+				addrbuf, isc_socket_getfd(sock));
+		}
+
 	} else {
 		isc_sockaddr_t sa_any;
 
@@ -2871,7 +2917,7 @@ dispatch_createudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		 */
 		isc_sockaddr_anyofpf(&sa_any, isc_sockaddr_pf(localaddr));
 		if (!isc_sockaddr_eqaddr(&sa_any, localaddr)) {
-			result = open_socket(sockmgr, localaddr, 0, &sock);
+			result = open_socket(sockmgr, localaddr, 0, &sock, NULL);
 			if (sock != NULL)
 				isc_socket_detach(&sock);
 			if (result != ISC_R_SUCCESS)
@@ -2938,6 +2984,7 @@ dispatch_createudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		dispatch_log(disp, LVL(90), "created socket %p", disp->socket);
 
 	*dispp = disp;
+
 	return (result);
 
 	/*
diff --git a/lib/dns/include/dns/dispatch.h b/lib/dns/include/dns/dispatch.h
index b9f68426be..b0c59e54ba 100644
--- a/lib/dns/include/dns/dispatch.h
+++ b/lib/dns/include/dns/dispatch.h
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: dispatch.h,v 1.62 2009/01/27 23:47:54 tbox Exp $ */
+/* $Id: dispatch.h,v 1.63 2011/07/28 04:04:37 each Exp $ */
 
 #ifndef DNS_DISPATCH_H
 #define DNS_DISPATCH_H 1
@@ -245,6 +245,15 @@ dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
 		    unsigned int buckets, unsigned int increment,
 		    unsigned int attributes, unsigned int mask,
 		    dns_dispatch_t **dispp);
+
+isc_result_t
+dns_dispatch_getudp_dup(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
+		    isc_taskmgr_t *taskmgr, isc_sockaddr_t *localaddr,
+		    unsigned int buffersize,
+		    unsigned int maxbuffers, unsigned int maxrequests,
+		    unsigned int buckets, unsigned int increment,
+		    unsigned int attributes, unsigned int mask,
+		    dns_dispatch_t **dispp, dns_dispatch_t *dup);
 /*%<
  * Attach to existing dns_dispatch_t if one is found with dns_dispatchmgr_find,
  * otherwise create a new UDP dispatch.
diff --git a/lib/isc/include/isc/namespace.h b/lib/isc/include/isc/namespace.h
index bc5ab60786..427e332a18 100644
--- a/lib/isc/include/isc/namespace.h
+++ b/lib/isc/include/isc/namespace.h
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: namespace.h,v 1.9 2010/12/04 13:25:59 marka Exp $ */
+/* $Id: namespace.h,v 1.10 2011/07/28 04:04:37 each Exp $ */
 
 #ifndef ISCAPI_NAMESPACE_H
 #define ISCAPI_NAMESPACE_H 1
@@ -88,6 +88,7 @@
 #define isc_mempool_getfillcount isc__mempool_getfillcount
 
 #define isc_socket_create isc__socket_create
+#define isc_socket_dup isc__socket_dup
 #define isc_socket_attach isc__socket_attach
 #define isc_socket_detach isc__socket_detach
 #define isc_socketmgr_create isc__socketmgr_create
diff --git a/lib/isc/include/isc/socket.h b/lib/isc/include/isc/socket.h
index c4ab0e2959..0307b8082d 100644
--- a/lib/isc/include/isc/socket.h
+++ b/lib/isc/include/isc/socket.h
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.h,v 1.94 2009/10/01 01:30:01 sar Exp $ */
+/* $Id: socket.h,v 1.95 2011/07/28 04:04:37 each Exp $ */
 
 #ifndef ISC_SOCKET_H
 #define ISC_SOCKET_H 1
@@ -449,6 +449,12 @@ isc_socket_create(isc_socketmgr_t *manager,
  *\li	#ISC_R_UNEXPECTED
  */
 
+isc_result_t
+isc_socket_dup(isc_socket_t *sock0, isc_socket_t **socketp);
+/*%<
+ * Duplicate an existing socket, reusing its file descriptor.
+ */
+
 void
 isc_socket_cancel(isc_socket_t *sock, isc_task_t *task,
 		  unsigned int how);
@@ -1102,6 +1108,11 @@ void *isc_socket_gettag(isc_socket_t *socket);
  * Get the tag associated with a socket, if any.
  */
 
+int isc_socket_getfd(isc_socket_t *socket);
+/*%<
+ * Get the file descriptor associated with a socket
+ */
+
 void
 isc__socketmgr_setreserved(isc_socketmgr_t *mgr, isc_uint32_t);
 /*%<
diff --git a/lib/isc/tests/Makefile.in b/lib/isc/tests/Makefile.in
index 15082373d3..063168d3ab 100644
--- a/lib/isc/tests/Makefile.in
+++ b/lib/isc/tests/Makefile.in
@@ -12,7 +12,7 @@
 # OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-# $Id: Makefile.in,v 1.2 2011/07/06 05:05:51 each Exp $
+# $Id: Makefile.in,v 1.3 2011/07/28 04:04:37 each Exp $
 
 srcdir =	@srcdir@
 VPATH =		@srcdir@
@@ -35,10 +35,10 @@ ISCDEPLIBS =	../libisc.@A@
 LIBS =		@LIBS@ @ATFLIBS@
 
 OBJS =		isctest.@O@
-SRCS =		isctest.c taskpool_test.c
+SRCS =		isctest.c taskpool_test.c socket_test.c
 
 SUBDIRS =
-TARGETS =	taskpool_test@EXEEXT@
+TARGETS =	taskpool_test@EXEEXT@ socket_test@EXEEXT@
 
 @BIND9_MAKE_RULES@
 
@@ -46,5 +46,9 @@ taskpool_test@EXEEXT@: taskpool_test.@O@ isctest.@O@ ${ISCDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
 			taskpool_test.@O@ isctest.@O@ ${ISCLIBS} ${LIBS}
 
+socket_test@EXEEXT@: socket_test.@O@ isctest.@O@ ${ISCDEPLIBS}
+	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
+			socket_test.@O@ isctest.@O@ ${ISCLIBS} ${LIBS}
+
 clean distclean::
 	rm -f ${TARGETS}
diff --git a/lib/isc/tests/isctest.c b/lib/isc/tests/isctest.c
index 6300b52161..6d0eecfe7f 100644
--- a/lib/isc/tests/isctest.c
+++ b/lib/isc/tests/isctest.c
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: isctest.c,v 1.2 2011/07/06 05:05:52 each Exp $ */
+/* $Id: isctest.c,v 1.3 2011/07/28 04:04:37 each Exp $ */
 
 /*! \file */
 
@@ -26,7 +26,10 @@
 #include <isc/hash.h>
 #include <isc/mem.h>
 #include <isc/os.h>
+#include <isc/socket.h>
 #include <isc/string.h>
+#include <isc/task.h>
+#include <isc/timer.h>
 #include <isc/util.h>
 
 #include "isctest.h"
@@ -35,6 +38,8 @@ isc_mem_t *mctx = NULL;
 isc_entropy_t *ectx = NULL;
 isc_log_t *lctx = NULL;
 isc_taskmgr_t *taskmgr = NULL;
+isc_timermgr_t *timermgr = NULL;
+isc_socketmgr_t *socketmgr = NULL;
 int ncpus;
 
 static isc_boolean_t hash_active = ISC_FALSE;
@@ -54,8 +59,37 @@ static isc_logcategory_t categories[] = {
 		{ NULL,              0 }
 };
 
+static void
+cleanup_managers() {
+	if (socketmgr != NULL)
+		isc_socketmgr_destroy(&socketmgr);
+	if (taskmgr != NULL)
+		isc_taskmgr_destroy(&taskmgr);
+	if (timermgr != NULL)
+		isc_timermgr_destroy(&timermgr);
+}
+
+static isc_result_t
+create_managers() {
+	isc_result_t result;
+#ifdef ISC_PLATFORM_USETHREADS
+	ncpus = isc_os_ncpus();
+#else
+	ncpus = 1;
+#endif
+
+	CHECK(isc_taskmgr_create(mctx, ncpus, 0, &taskmgr));
+	CHECK(isc_timermgr_create(mctx, &timermgr));
+	CHECK(isc_socketmgr_create(mctx, &socketmgr));
+	return (ISC_R_SUCCESS);
+
+  cleanup:
+	cleanup_managers();
+	return (result);
+}
+
 isc_result_t
-isc_test_begin(FILE *logfile) {
+isc_test_begin(FILE *logfile, isc_boolean_t start_managers) {
 	isc_result_t result;
 
 	isc_mem_debugging |= ISC_MEM_DEBUGRECORD;
@@ -90,7 +124,8 @@ isc_test_begin(FILE *logfile) {
 	ncpus = 1;
 #endif
 
-	CHECK(isc_taskmgr_create(mctx, ncpus, 0, &taskmgr));
+	if (start_managers)
+		CHECK(create_managers());
 
 	return (ISC_R_SUCCESS);
 
@@ -111,6 +146,9 @@ isc_test_end() {
 	}
 	if (ectx != NULL)
 		isc_entropy_detach(&ectx);
+
+	cleanup_managers();
+
 	if (mctx != NULL)
 		isc_mem_destroy(&mctx);
 }
diff --git a/lib/isc/tests/isctest.h b/lib/isc/tests/isctest.h
index 36b0852589..243e7feb15 100644
--- a/lib/isc/tests/isctest.h
+++ b/lib/isc/tests/isctest.h
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: isctest.h,v 1.2 2011/07/06 05:05:52 each Exp $ */
+/* $Id: isctest.h,v 1.3 2011/07/28 04:04:37 each Exp $ */
 
 /*! \file */
 
@@ -42,10 +42,12 @@ extern isc_mem_t *mctx;
 extern isc_entropy_t *ectx;
 extern isc_log_t *lctx;
 extern isc_taskmgr_t *taskmgr;
+isc_timermgr_t *timermgr;
+isc_socketmgr_t *socketmgr;
 extern int ncpus;
 
 isc_result_t
-isc_test_begin(FILE *logfile);
+isc_test_begin(FILE *logfile, isc_boolean_t start_managers);
 
 void
 isc_test_end(void);
diff --git a/lib/isc/tests/socket_test.c b/lib/isc/tests/socket_test.c
new file mode 100644
index 0000000000..3aaaf043e5
--- /dev/null
+++ b/lib/isc/tests/socket_test.c
@@ -0,0 +1,274 @@
+/*
+ * Copyright (C) 2011  Internet Systems Consortium, Inc. ("ISC")
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: socket_test.c,v 1.2 2011/07/28 04:04:37 each Exp $ */
+
+/*! \file */
+
+#include <config.h>
+
+#include <atf-c.h>
+
+#include <unistd.h>
+#include <time.h>
+
+#include <isc/socket.h>
+
+#include "../task_p.h"
+#include "isctest.h"
+
+/*
+ * Helper functions
+ */
+typedef struct {
+	isc_boolean_t done;
+	isc_result_t result;
+} completion_t;
+
+static void
+completion_init(completion_t *completion) {
+	completion->done = ISC_FALSE;
+}
+
+static void
+event_done(isc_task_t *task, isc_event_t *event) {
+	isc_socketevent_t *dev;
+	completion_t *completion = event->ev_arg;
+
+	UNUSED(task);
+
+	dev = (isc_socketevent_t *) event;
+	completion->result = dev->result;
+	completion->done = ISC_TRUE;
+	isc_event_free(&event);
+}
+
+static void
+nap(isc_uint32_t usec) {
+#ifdef HAVE_NANOSLEEP
+	struct timespec ts;
+
+	ts.tv_sec = usec / 1000000;
+	ts.tv_nsec = (usec % 1000000) * 1000;
+	nanosleep(&ts, NULL);
+#elif HAVE_USLEEP
+	usleep(usec);
+#else
+	/* Round up to the nearest second and sleep, instead */
+	sleep((usec / 1000000) + 1);
+#endif
+}
+
+static isc_result_t
+waitfor(completion_t *completion) {
+	int i = 0;
+	while (!completion->done && i++ < 5000) {
+#ifndef ISC_PLATFORM_USETHREADS
+		while (isc__taskmgr_ready(taskmgr))
+			isc__taskmgr_dispatch(taskmgr);
+#endif
+		nap(1000);
+	}
+	if (completion->done)
+		return (ISC_R_SUCCESS);
+	return (ISC_R_FAILURE);
+}
+
+/*
+ * Individual unit tests
+ */
+
+/* Test UDP sendto/recv (IPv4) */
+ATF_TC(udp_sendto);
+ATF_TC_HEAD(udp_sendto, tc) {
+	atf_tc_set_md_var(tc, "descr", "UDP sendto/recv");
+}
+ATF_TC_BODY(udp_sendto, tc) {
+	isc_result_t result;
+	isc_sockaddr_t addr1, addr2;
+	struct in_addr in;
+	isc_socket_t *s1 = NULL, *s2 = NULL;
+	isc_task_t *task = NULL;
+	char sendbuf[BUFSIZ], recvbuf[BUFSIZ];
+	completion_t completion;
+	isc_region_t r;
+
+	UNUSED(tc);
+
+	result = isc_test_begin(NULL, ISC_TRUE);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	/*
+	 * Create two sockets: 127.0.0.1/5444 and 127.0.0.1/5445, talking to
+	 * each other.
+	 */
+	in.s_addr = inet_addr("127.0.0.1");
+	isc_sockaddr_fromin(&addr1, &in, 5444);
+	isc_sockaddr_fromin(&addr2, &in, 5445);
+
+	result = isc_socket_create(socketmgr, PF_INET, isc_sockettype_udp, &s1);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+	result = isc_socket_bind(s1, &addr1, ISC_SOCKET_REUSEADDRESS);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	result = isc_socket_create(socketmgr, PF_INET, isc_sockettype_udp, &s2);
+	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_task_create(taskmgr, 0, &task);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	strcpy(sendbuf, "Hello");
+	r.base = (void *) sendbuf;
+	r.length = strlen(sendbuf) + 1;
+
+	completion_init(&completion);
+	result = isc_socket_sendto(s1, &r, task, event_done, &completion,
+				   &addr2, NULL);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+
+	r.base = (void *) recvbuf;
+	r.length = BUFSIZ;
+	completion_init(&completion);
+	result = isc_socket_recv(s2, &r, 1, task, event_done, &completion);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+	ATF_CHECK_STREQ(recvbuf, "Hello");
+
+	isc_task_detach(&task);
+
+	isc_socket_detach(&s1);
+	isc_socket_detach(&s2);
+
+	isc_test_end();
+}
+
+/* Test UDP sendto/recv with duplicated socket */
+ATF_TC(udp_dup);
+ATF_TC_HEAD(udp_dup, tc) {
+	atf_tc_set_md_var(tc, "descr", "duplicated socket sendto/recv");
+}
+ATF_TC_BODY(udp_dup, tc) {
+	isc_result_t result;
+	isc_sockaddr_t addr1, addr2;
+	struct in_addr in;
+	isc_socket_t *s1 = NULL, *s2 = NULL, *s3 = NULL;
+	isc_task_t *task = NULL;
+	char sendbuf[BUFSIZ], recvbuf[BUFSIZ];
+	completion_t completion;
+	isc_region_t r;
+
+	UNUSED(tc);
+
+	result = isc_test_begin(NULL, ISC_TRUE);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	/*
+	 * Create two sockets: 127.0.0.1/5444 and 127.0.0.1/5445, talking to
+	 * each other.
+	 */
+	in.s_addr = inet_addr("127.0.0.1");
+	isc_sockaddr_fromin(&addr1, &in, 5444);
+	isc_sockaddr_fromin(&addr2, &in, 5445);
+
+	result = isc_socket_create(socketmgr, PF_INET, isc_sockettype_udp, &s1);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+	result = isc_socket_bind(s1, &addr1, ISC_SOCKET_REUSEADDRESS);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	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);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+	
+	result = isc_task_create(taskmgr, 0, &task);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	strcpy(sendbuf, "Hello");
+	r.base = (void *) sendbuf;
+	r.length = strlen(sendbuf) + 1;
+
+	completion_init(&completion);
+	result = isc_socket_sendto(s1, &r, task, event_done, &completion,
+				   &addr2, NULL);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+
+	strcpy(sendbuf, "World");
+	r.base = (void *) sendbuf;
+	r.length = strlen(sendbuf) + 1;
+
+	completion_init(&completion);
+	result = isc_socket_sendto(s1, &r, task, event_done, &completion,
+				   &addr2, NULL);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+
+	r.base = (void *) recvbuf;
+	r.length = BUFSIZ;
+	completion_init(&completion);
+	result = isc_socket_recv(s2, &r, 1, task, event_done, &completion);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+	ATF_CHECK_STREQ(recvbuf, "Hello");
+
+	r.base = (void *) recvbuf;
+	r.length = BUFSIZ;
+	completion_init(&completion);
+	result = isc_socket_recv(s3, &r, 1, task, event_done, &completion);
+	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
+	waitfor(&completion);
+	ATF_CHECK(completion.done);
+	ATF_CHECK_EQ(completion.result, ISC_R_SUCCESS);
+	ATF_CHECK_STREQ(recvbuf, "World");
+
+	isc_task_detach(&task);
+
+	isc_socket_detach(&s1);
+	isc_socket_detach(&s2);
+	isc_socket_detach(&s3);
+
+	isc_test_end();
+}
+
+
+/*
+ * Main
+ */
+ATF_TP_ADD_TCS(tp) {
+	ATF_TP_ADD_TC(tp, udp_sendto);
+	ATF_TP_ADD_TC(tp, udp_dup);
+
+	return (atf_no_error());
+}
+
diff --git a/lib/isc/tests/taskpool_test.c b/lib/isc/tests/taskpool_test.c
index 63bce41d7c..ab80f452bb 100644
--- a/lib/isc/tests/taskpool_test.c
+++ b/lib/isc/tests/taskpool_test.c
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: taskpool_test.c,v 1.2 2011/07/06 05:05:52 each Exp $ */
+/* $Id: taskpool_test.c,v 1.3 2011/07/28 04:04:37 each Exp $ */
 
 /*! \file */
 
@@ -44,7 +44,7 @@ ATF_TC_BODY(create_pool, tc) {
 
 	UNUSED(tc);
 
-	result = isc_test_begin(NULL);
+	result = isc_test_begin(NULL, ISC_TRUE);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
 
 	result = isc_taskpool_create(taskmgr, mctx, 8, 2, &pool);
@@ -68,7 +68,7 @@ ATF_TC_BODY(expand_pool, tc) {
 
 	UNUSED(tc);
 
-	result = isc_test_begin(NULL);
+	result = isc_test_begin(NULL, ISC_TRUE);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
 
 	result = isc_taskpool_create(taskmgr, mctx, 10, 2, &pool1);
@@ -121,7 +121,7 @@ ATF_TC_BODY(get_tasks, tc) {
 
 	UNUSED(tc);
 
-	result = isc_test_begin(NULL);
+	result = isc_test_begin(NULL, ISC_TRUE);
 	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
 
 	result = isc_taskpool_create(taskmgr, mctx, 2, 2, &pool);
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 9b73994d8b..796044d5b2 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 1.340 2011/07/21 23:47:53 tbox Exp $ */
+/* $Id: socket.c,v 1.341 2011/07/28 04:04:37 each Exp $ */
 
 /*! \file */
 
@@ -334,7 +334,8 @@ struct isc__socket {
 				listener : 1, /* listener socket */
 				connected : 1,
 				connecting : 1, /* connect pending */
-				bound : 1; /* bound to local addr */
+				bound : 1, /* bound to local addr */
+				dupped : 1;
 
 #ifdef ISC_NET_RECVOVERFLOW
 	unsigned char		overflow; /* used for MSG_TRUNC fake */
@@ -428,6 +429,10 @@ static isc__socketmgr_t *socketmgr = NULL;
 # define MAXSCATTERGATHER_RECV	(ISC_SOCKET_MAXSCATTERGATHER)
 #endif
 
+static isc_result_t socket_create(isc_socketmgr_t *manager0, int pf,
+				  isc_sockettype_t type,
+				  isc_socket_t **socketp,
+				  isc_socket_t *dup_socket);
 static void send_recvdone_event(isc__socket_t *, isc_socketevent_t **);
 static void send_senddone_event(isc__socket_t *, isc_socketevent_t **);
 static void free_socket(isc__socket_t **);
@@ -2045,6 +2050,7 @@ allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
 	sock->manager = manager;
 	sock->type = type;
 	sock->fd = -1;
+	sock->dupped = 0;
 	sock->statsindex = NULL;
 
 	ISC_LINK_INIT(sock, link);
@@ -2221,7 +2227,8 @@ clear_bsdcompat(void) {
 #endif
 
 static isc_result_t
-opensocket(isc__socketmgr_t *manager, isc__socket_t *sock) {
+opensocket(isc__socketmgr_t *manager, isc__socket_t *sock,
+	   isc__socket_t *dup_socket) {
 	char strbuf[ISC_STRERRORSIZE];
 	const char *err = "socket";
 	int tries = 0;
@@ -2234,22 +2241,28 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock) {
 #endif
 
  again:
-	switch (sock->type) {
-	case isc_sockettype_udp:
-		sock->fd = socket(sock->pf, SOCK_DGRAM, IPPROTO_UDP);
-		break;
-	case isc_sockettype_tcp:
-		sock->fd = socket(sock->pf, SOCK_STREAM, IPPROTO_TCP);
-		break;
-	case isc_sockettype_unix:
-		sock->fd = socket(sock->pf, SOCK_STREAM, 0);
-		break;
-	case isc_sockettype_fdwatch:
-		/*
-		 * We should not be called for isc_sockettype_fdwatch sockets.
-		 */
-		INSIST(0);
-		break;
+	if (dup_socket == NULL) {
+		switch (sock->type) {
+		case isc_sockettype_udp:
+			sock->fd = socket(sock->pf, SOCK_DGRAM, IPPROTO_UDP);
+			break;
+		case isc_sockettype_tcp:
+			sock->fd = socket(sock->pf, SOCK_STREAM, IPPROTO_TCP);
+			break;
+		case isc_sockettype_unix:
+			sock->fd = socket(sock->pf, SOCK_STREAM, 0);
+			break;
+		case isc_sockettype_fdwatch:
+			/*
+			 * We should not be called for isc_sockettype_fdwatch
+			 * sockets.
+			 */
+			INSIST(0);
+			break;
+		}
+	} else {
+		sock->fd = dup(dup_socket->fd);
+		sock->dupped = 1;
 	}
 	if (sock->fd == -1 && errno == EINTR && tries++ < 42)
 		goto again;
@@ -2326,6 +2339,9 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock) {
 		}
 	}
 
+	if (dup_socket != NULL)
+		goto setup_done;
+
 	if (make_nonblock(sock->fd) != ISC_R_SUCCESS) {
 		(void)close(sock->fd);
 		return (ISC_R_UNEXPECTED);
@@ -2509,20 +2525,21 @@ opensocket(isc__socketmgr_t *manager, isc__socket_t *sock) {
 	}
 #endif /* defined(USE_CMSG) || defined(SO_RCVBUF) */
 
+setup_done:
 	inc_stats(manager->stats, sock->statsindex[STATID_OPEN]);
 
 	return (ISC_R_SUCCESS);
 }
 
-/*%
- * Create a new 'type' socket managed by 'manager'.  Events
- * will be posted to 'task' and when dispatched 'action' will be
- * called with 'arg' as the arg value.  The new socket is returned
- * in 'socketp'.
+/*
+ * Create a 'type' socket or duplicate an existing socket, managed
+ * by 'manager'.  Events will be posted to 'task' and when dispatched
+ * 'action' will be called with 'arg' as the arg value.  The new
+ * socket is returned in 'socketp'.
  */
-ISC_SOCKETFUNC_SCOPE isc_result_t
-isc__socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
-		   isc_socket_t **socketp)
+static isc_result_t
+socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
+	      isc_socket_t **socketp, isc_socket_t *dup_socket)
 {
 	isc__socket_t *sock = NULL;
 	isc__socketmgr_t *manager = (isc__socketmgr_t *)manager0;
@@ -2554,7 +2571,8 @@ isc__socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
 	}
 
 	sock->pf = pf;
-	result = opensocket(manager, sock);
+
+	result = opensocket(manager, sock, (isc__socket_t *)dup_socket);
 	if (result != ISC_R_SUCCESS) {
 		inc_stats(manager->stats, sock->statsindex[STATID_OPENFAIL]);
 		free_socket(&sock);
@@ -2589,11 +2607,40 @@ isc__socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
 	UNLOCK(&manager->lock);
 
 	socket_log(sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
-		   ISC_MSG_CREATED, "created");
+		   ISC_MSG_CREATED, dup_socket == NULL ? "dupped" : "created");
 
 	return (ISC_R_SUCCESS);
 }
 
+/*%
+ * Create a new 'type' socket managed by 'manager'.  Events
+ * will be posted to 'task' and when dispatched 'action' will be
+ * called with 'arg' as the arg value.  The new socket is returned
+ * in 'socketp'.
+ */
+ISC_SOCKETFUNC_SCOPE isc_result_t
+isc__socket_create(isc_socketmgr_t *manager0, int pf, isc_sockettype_t type,
+		   isc_socket_t **socketp)
+{
+	return (socket_create(manager0, pf, type, socketp, NULL));
+}
+
+/*%
+ * Duplicate an existing socket.  The new socket is returned
+ * in 'socketp'.
+ */
+ISC_SOCKETFUNC_SCOPE isc_result_t
+isc__socket_dup(isc_socket_t *sock0, isc_socket_t **socketp) {
+	isc__socket_t *sock = (isc__socket_t *)sock0;
+
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(socketp != NULL && *socketp == NULL);
+
+	return (socket_create((isc_socketmgr_t *) sock->manager,
+                              sock->pf, sock->type, socketp,
+                              sock0));
+}
+
 #ifdef BIND9
 ISC_SOCKETFUNC_SCOPE isc_result_t
 isc__socket_open(isc_socket_t *sock0) {
@@ -2612,7 +2659,7 @@ isc__socket_open(isc_socket_t *sock0) {
 	 */
 	REQUIRE(sock->fd == -1);
 
-	result = opensocket(sock->manager, sock);
+	result = opensocket(sock->manager, sock, NULL);
 	if (result != ISC_R_SUCCESS)
 		sock->fd = -1;
 
@@ -2792,6 +2839,7 @@ isc__socket_close(isc_socket_t *sock0) {
 	int fd;
 	isc__socketmgr_t *manager;
 
+	fflush(stdout);
 	REQUIRE(VALID_SOCKET(sock));
 
 	LOCK(&sock->lock);
@@ -2812,6 +2860,7 @@ isc__socket_close(isc_socket_t *sock0) {
 	manager = sock->manager;
 	fd = sock->fd;
 	sock->fd = -1;
+	sock->dupped = 0;
 	memset(sock->name, 0, sizeof(sock->name));
 	sock->tag = NULL;
 	sock->listener = 0;
@@ -4977,48 +5026,49 @@ isc__socket_bind(isc_socket_t *sock0, isc_sockaddr_t *sockaddr,
 		UNLOCK(&sock->lock);
 		return (ISC_R_FAMILYMISMATCH);
 	}
-	/*
-	 * Only set SO_REUSEADDR when we want a specific port.
-	 */
+	if (!sock->dupped) {
+		/*
+		 * Only set SO_REUSEADDR when we want a specific port.
+		 */
 #ifdef AF_UNIX
-	if (sock->pf == AF_UNIX)
-		goto bind_socket;
+		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... */
-	}
+		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:
+	 bind_socket:
 #endif
-	if (bind(sock->fd, &sockaddr->type.sa, sockaddr->length) < 0) {
-		inc_stats(sock->manager->stats,
-			  sock->statsindex[STATID_BINDFAIL]);
+		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);
+			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;
@@ -5826,6 +5876,13 @@ isc__socket_register() {
 }
 #endif
 
+int
+isc_socket_getfd(isc_socket_t *socket0) {
+	isc__socket_t *socket = (isc__socket_t *)socket0;
+
+	return ((short) socket->fd);
+}
+
 #if defined(HAVE_LIBXML2) && defined(BIND9)
 
 static const char *
diff --git a/lib/isc/win32/libisc.def b/lib/isc/win32/libisc.def
index 740f3cefc2..3c20d99a3d 100644
--- a/lib/isc/win32/libisc.def
+++ b/lib/isc/win32/libisc.def
@@ -88,6 +88,7 @@ isc__socket_close
 isc__socket_connect
 isc__socket_create
 isc__socket_detach
+isc__socket_dup
 isc__socket_filter
 isc__socket_getname
 isc__socket_getpeername
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index bf915f7f0d..4343454a44 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 1.87 2010/12/09 06:08:05 marka Exp $ */
+/* $Id: socket.c,v 1.88 2011/07/28 04:04:37 each Exp $ */
 
 /* This code uses functions which are only available on Server 2003 and
  * higher, and Windows XP and higher.
@@ -265,7 +265,8 @@ struct isc_socket {
 	unsigned int		listener : 1,	/* listener socket */
 				connected : 1,
 				pending_connect : 1, /* connect pending */
-				bound : 1;	/* bound to local addr */
+				bound : 1,	/* bound to local addr */
+				dupped : 1;     /* created by isc_socket_dup() */
 	unsigned int		pending_iocp;	/* Should equal the counters below. Debug. */
 	unsigned int		pending_recv;  /* Number of outstanding recv() calls. */
 	unsigned int		pending_send;  /* Number of outstanding send() calls. */
@@ -351,6 +352,10 @@ enum {
 #define MAXSCATTERGATHER_SEND	(ISC_SOCKET_MAXSCATTERGATHER)
 #define MAXSCATTERGATHER_RECV	(ISC_SOCKET_MAXSCATTERGATHER)
 
+static isc_result_t socket_create(isc_socketmgr_t *manager0, int pf,
+				  isc_sockettype_t type,
+				  isc_socket_t **socketp,
+				  isc_socket_t *dup_socket);
 static isc_threadresult_t WINAPI SocketIoThread(LPVOID ThreadContext);
 static void maybe_free_socket(isc_socket_t **, int);
 static void free_socket(isc_socket_t **, int);
@@ -1461,6 +1466,7 @@ allocate_socket(isc_socketmgr_t *manager, isc_sockettype_t type,
 	sock->connected = 0;
 	sock->pending_connect = 0;
 	sock->bound = 0;
+	sock->dupped = 0;
 	memset(sock->name, 0, sizeof(sock->name));	// zero the name field
 	_set_state(sock, SOCK_INITIALIZED);
 
@@ -1623,9 +1629,10 @@ free_socket(isc_socket_t **sockp, int lineno) {
  * called with 'arg' as the arg value.  The new socket is returned
  * in 'socketp'.
  */
-isc_result_t
-isc__socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
-		  isc_socket_t **socketp) {
+static isc_result_t
+socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
+	      isc_socket_t **socketp, isc_socket_t *dup_socket)
+{
 	isc_socket_t *sock = NULL;
 	isc_result_t result;
 #if defined(USE_CMSG)
@@ -1647,27 +1654,35 @@ isc__socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
 		return (result);
 
 	sock->pf = pf;
-	switch (type) {
-	case isc_sockettype_udp:
-		sock->fd = socket(pf, SOCK_DGRAM, IPPROTO_UDP);
-		if (sock->fd != INVALID_SOCKET) {
-			result = connection_reset_fix(sock->fd);
-			if (result != ISC_R_SUCCESS) {
-				socket_log(__LINE__, sock, NULL, EVENT, NULL, 0, 0,
-					"closed %d %d %d con_reset_fix_failed",
-					sock->pending_recv, sock->pending_send,
-					sock->references);
-				closesocket(sock->fd);
-				_set_state(sock, SOCK_CLOSED);
-				sock->fd = INVALID_SOCKET;
-				free_socket(&sock, __LINE__);
-				return (result);
+	if (dup_socket == NULL) {
+		switch (type) {
+		case isc_sockettype_udp:
+			sock->fd = socket(pf, SOCK_DGRAM, IPPROTO_UDP);
+			if (sock->fd != INVALID_SOCKET) {
+				result = connection_reset_fix(sock->fd);
+				if (result != ISC_R_SUCCESS) {
+					socket_log(__LINE__, sock,
+						NULL, EVENT, NULL, 0, 0,
+						"closed %d %d %d "
+						"con_reset_fix_failed",
+						sock->pending_recv,
+						sock->pending_send,
+						sock->references);
+					closesocket(sock->fd);
+					_set_state(sock, SOCK_CLOSED);
+					sock->fd = INVALID_SOCKET;
+					free_socket(&sock, __LINE__);
+					return (result);
+				}
 			}
+			break;
+		case isc_sockettype_tcp:
+			sock->fd = socket(pf, SOCK_STREAM, IPPROTO_TCP);
+			break;
 		}
-		break;
-	case isc_sockettype_tcp:
-		sock->fd = socket(pf, SOCK_STREAM, IPPROTO_TCP);
-		break;
+	} else {
+		sock->fd = dup(dup_socket->fd);
+		sock->dupped = 1;
 	}
 
 	if (sock->fd == INVALID_SOCKET) {
@@ -1786,12 +1801,29 @@ isc__socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
 	InterlockedIncrement(&manager->totalSockets);
 	UNLOCK(&manager->lock);
 
-	socket_log(__LINE__, sock, NULL, CREATION, isc_msgcat, ISC_MSGSET_SOCKET,
-		   ISC_MSG_CREATED, "created %u type %u", sock->fd, type);
+	socket_log(__LINE__, sock, NULL, CREATION, isc_msgcat,
+		   ISC_MSGSET_SOCKET, ISC_MSG_CREATED,
+		   "created %u type %u", sock->fd, type);
 
 	return (ISC_R_SUCCESS);
 }
 
+isc_result_t
+isc__socket_create(isc_socketmgr_t *manager, int pf, isc_sockettype_t type,
+		   isc_socket_t **socketp)
+{
+	return (socket_create(manager, pf, type, socketp, NULL));
+}
+
+isc_result_t
+isc__socket_dup(isc_socket_t *sock, isc_socket_t **socketp) {
+	REQUIRE(VALID_SOCKET(sock));
+	REQUIRE(socketp != NULL && *socketp == NULL);
+
+	return (socket_create(sock->manager, sock->pf, sock->type,
+			      socketp, sock));
+}
+
 isc_result_t
 isc_socket_open(isc_socket_t *sock) {
 	REQUIRE(VALID_SOCKET(sock));