diff -up dhcp-4.2.0/server/dhcpv6.c.noprefixavail dhcp-4.2.0/server/dhcpv6.c
--- dhcp-4.2.0/server/dhcpv6.c.noprefixavail	2010-10-07 13:48:45.000000000 +0200
+++ dhcp-4.2.0/server/dhcpv6.c	2010-10-13 11:00:25.000000000 +0200
@@ -1134,7 +1134,7 @@ try_client_v6_prefix(struct iasubopt **p
 		return DHCP_R_INVALIDARG;
 	}
 	tmp_plen = (int) requested_pref->data[0];
-	if ((tmp_plen < 3) || (tmp_plen > 128)) {
+	if ((tmp_plen < 3) || (tmp_plen > 128) ||((int)tmp_plen != pool->units)) {
 		return ISC_R_FAILURE;
 	}
 	memcpy(&tmp_pref, requested_pref->data + 1, sizeof(tmp_pref));
@@ -1147,9 +1147,8 @@ try_client_v6_prefix(struct iasubopt **p
 		return ISC_R_FAILURE;
 	}
 
-	if (((int)tmp_plen != pool->units) ||
-	    !ipv6_in_pool(&tmp_pref, pool)) {
-		return ISC_R_FAILURE;
+	if (!ipv6_in_pool(&tmp_pref, pool)) {
+		return ISC_R_ADDRNOTAVAIL;
 	}
 
 	if (prefix6_exists(pool, &tmp_pref, tmp_plen)) {
@@ -1409,13 +1408,6 @@ lease_to_client(struct data_string *repl
 		if ((status != ISC_R_SUCCESS) &&
 		    (status != ISC_R_NORESOURCES))
 			goto exit;
-
-		/*
-		 * If any prefix cannot be given to any IA_PD, then
-		 * set the NoPrefixAvail status code.
-		 */
-		if (reply.client_resources == 0)
-			no_resources_avail = ISC_TRUE;
 	}
 
 	/*
@@ -1549,36 +1541,6 @@ lease_to_client(struct data_string *repl
 					       reply.opt_state, reply.packet,
 					       required_opts_NAA,
 					       NULL);
-	} else if (no_resources_avail && (reply.ia_count == 0) &&
-		   (reply.packet->dhcpv6_msg_type == DHCPV6_SOLICIT))
-	{
-		/* Set the NoPrefixAvail status code. */
-		if (!set_status_code(STATUS_NoPrefixAvail,
-				     "No prefixes available for this "
-				     "interface.", reply.opt_state)) {
-			log_error("lease_to_client: Unable to set "
-				  "NoPrefixAvail status code.");
-			goto exit;
-		}
-
-		/* Rewind the cursor to the start. */
-		reply.cursor = REPLY_OPTIONS_INDEX;
-
-		/*
-		 * Produce an advertise that includes only:
-		 *
-		 * Status code.
-		 * Server DUID.
-		 * Client DUID.
-		 */
-		reply.buf.reply.msg_type = DHCPV6_ADVERTISE;
-		reply.cursor += store_options6((char *)reply.buf.data +
-							reply.cursor,
-					       sizeof(reply.buf) -
-					       		reply.cursor,
-					       reply.opt_state, reply.packet,
-					       required_opts_NAA,
-					       NULL);
 	} else {
 		/*
 		 * Having stored the client's IA's, store any options that
@@ -2793,16 +2755,18 @@ find_client_temporaries(struct reply_sta
  */
 static isc_result_t
 reply_process_try_addr(struct reply_state *reply, struct iaddr *addr) {
-	isc_result_t status = ISC_R_NORESOURCES;
+	isc_result_t status = ISC_R_ADDRNOTAVAIL;
 	struct ipv6_pool *pool;
 	int i;
 	struct data_string data_addr;
 
 	if ((reply == NULL) || (reply->shared == NULL) ||
-	    (reply->shared->ipv6_pools == NULL) || (addr == NULL) ||
-	    (reply->lease != NULL))
+	    (addr == NULL) || (reply->lease != NULL))
 		return DHCP_R_INVALIDARG;
 
+	if (reply->shared->ipv6_pools == NULL)
+		return ISC_R_ADDRNOTAVAIL;
+
 	memset(&data_addr, 0, sizeof(data_addr));
 	data_addr.len = addr->len;
 	data_addr.data = addr->iabuf;
@@ -3314,7 +3278,9 @@ reply_process_ia_pd(struct reply_state *
 		if (status == ISC_R_CANCELED)
 			break;
 
-		if ((status != ISC_R_SUCCESS) && (status != ISC_R_ADDRINUSE))
+		if ((status != ISC_R_SUCCESS) &&
+		    (status != ISC_R_ADDRINUSE) &&
+		    (status != ISC_R_ADDRNOTAVAIL))
 			goto cleanup;
 	}
 
@@ -3594,7 +3560,8 @@ reply_process_prefix(struct reply_state 
 
 			/* Either error out or skip this prefix. */
 			if ((status != ISC_R_SUCCESS) && 
-			    (status != ISC_R_ADDRINUSE)) 
+			    (status != ISC_R_ADDRINUSE) &&
+			    (status != ISC_R_ADDRNOTAVAIL))
 				goto cleanup;
 
 			if (reply->lease == NULL) {
@@ -3773,16 +3740,18 @@ prefix_is_owned(struct reply_state *repl
 static isc_result_t
 reply_process_try_prefix(struct reply_state *reply,
 			 struct iaddrcidrnet *pref) {
-	isc_result_t status = ISC_R_NORESOURCES;
+	isc_result_t status = ISC_R_ADDRNOTAVAIL;
 	struct ipv6_pool *pool;
 	int i;
 	struct data_string data_pref;
 
 	if ((reply == NULL) || (reply->shared == NULL) ||
-	    (reply->shared->ipv6_pools == NULL) || (pref == NULL) ||
-	    (reply->lease != NULL))
+	    (pref == NULL) || (reply->lease != NULL))
 		return DHCP_R_INVALIDARG;
 
+	if (reply->shared->ipv6_pools == NULL)
+		return ISC_R_ADDRNOTAVAIL;
+
 	memset(&data_pref, 0, sizeof(data_pref));
 	data_pref.len = 17;
 	if (!buffer_allocate(&data_pref.buffer, data_pref.len, MDL)) {