diff --git a/src/dns.c b/src/dns.c
index 527ccae..327bf5f 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -927,12 +927,12 @@ static int _dns_decode_qr_head(struct dns_context *context, char *domain, int do
 	*/
 	ret = _dns_decode_domain(context, domain, domain_size);
 	if (ret < 0) {
-		tlog(TLOG_ERROR, "decode domain failed.");
+		tlog(TLOG_WARN, "decode domain failed.");
 		return -1;
 	}
 
 	if (_dns_left_len(context) < 4) {
-		tlog(TLOG_ERROR, "left length is not enough, %s.", domain);
+		tlog(TLOG_WARN, "left length is not enough, %s.", domain);
 		return -1;
 	}
 
@@ -1542,7 +1542,7 @@ static int _dns_decode_body(struct dns_context *context)
 	for (i = 0; i < head->qdcount; i++) {
 		ret = _dns_decode_qd(context);
 		if (ret < 0) {
-			tlog(TLOG_ERROR, "decode qd failed.");
+			tlog(TLOG_WARN, "decode qd failed.");
 			return -1;
 		}
 		head->qdcount--;
@@ -1551,7 +1551,7 @@ static int _dns_decode_body(struct dns_context *context)
 	for (i = 0; i < head->ancount; i++) {
 		ret = _dns_decode_an(context, DNS_RRS_AN);
 		if (ret < 0) {
-			tlog(TLOG_ERROR, "decode an failed.");
+			tlog(TLOG_WARN, "decode an failed.");
 			return -1;
 		}
 		head->ancount--;
@@ -1560,7 +1560,7 @@ static int _dns_decode_body(struct dns_context *context)
 	for (i = 0; i < head->nscount; i++) {
 		ret = _dns_decode_an(context, DNS_RRS_NS);
 		if (ret < 0) {
-			tlog(TLOG_ERROR, "decode ns failed.");
+			tlog(TLOG_WARN, "decode ns failed.");
 			return -1;
 		}
 		head->nscount--;
@@ -1569,7 +1569,7 @@ static int _dns_decode_body(struct dns_context *context)
 	for (i = 0; i < head->nrcount; i++) {
 		ret = _dns_decode_an(context, DNS_RRS_NR);
 		if (ret < 0) {
-			tlog(TLOG_ERROR, "decode nr failed.");
+			tlog(TLOG_WARN, "decode nr failed.");
 			return -1;
 		}
 		head->nrcount--;
@@ -1669,7 +1669,7 @@ int dns_decode(struct dns_packet *packet, int maxsize, unsigned char *data, int
 
 	ret = _dns_decode_body(&context);
 	if (ret < 0) {
-		tlog(TLOG_ERROR, "decode body failed.\n");
+		tlog(TLOG_WARN, "decode body failed.\n");
 		return -1;
 	}
 
diff --git a/src/dns_client.c b/src/dns_client.c
index 2fe9e51..a8a9d4b 100644
--- a/src/dns_client.c
+++ b/src/dns_client.c
@@ -61,6 +61,7 @@ struct dns_client {
 	/* query list */
 	pthread_mutex_t dns_request_lock;
 	struct list_head dns_request_list;
+	atomic_t dns_server_num;
 
 	/* query doman hash table, key: sid + domain */
 	pthread_mutex_t domain_map_lock;
@@ -234,6 +235,8 @@ int _dns_client_server_add(char *server_ip, struct addrinfo *gai, dns_server_typ
 	pthread_mutex_lock(&client.server_list_lock);
 	list_add(&server_info->list, &client.dns_server_list);
 	pthread_mutex_unlock(&client.server_list_lock);
+
+	atomic_inc(&client.dns_server_num);
 	return 0;
 errout:
 	if (server_info) {
@@ -299,6 +302,7 @@ int _dns_client_server_remove(char *server_ip, struct addrinfo *gai, dns_server_
 			tlog(TLOG_ERROR, "stop ping failed.\n");
 		}
 		free(server_info);
+		atomic_dec(&client.dns_server_num);
 		return 0;
 	}
 	pthread_mutex_unlock(&client.server_list_lock);
@@ -361,6 +365,11 @@ int dns_remove_server(char *server_ip, int port, dns_server_type_t server_type)
 	return _dns_client_server_operate(server_ip, port, server_type, 1);
 }
 
+int dns_server_num(void)
+{
+	return atomic_read(&client.dns_server_num);
+}
+
 void _dns_client_query_get(struct dns_query_struct *query)
 {
 	atomic_inc(&query->refcnt);
@@ -560,7 +569,9 @@ static int _dns_client_recv(unsigned char *inpacket, int inpacket_len, struct so
 	/* decode domain from udp packet */
 	len = dns_decode(packet, DNS_PACKSIZE, inpacket, inpacket_len);
 	if (len != 0) {
-		tlog(TLOG_ERROR, "decode failed, packet len = %d, tc=%d, %d\n", inpacket_len, packet->head.tc, packet->head.id);
+		char host_name[DNS_MAX_CNAME_LEN];
+		tlog(TLOG_ERROR, "decode failed, packet len = %d, tc = %d, id = %d, from = %s\n", inpacket_len, packet->head.tc, packet->head.id,
+			gethost_by_addr(host_name, from, from_len));
 		return -1;
 	}
 
@@ -1125,6 +1136,7 @@ int dns_client_init()
 
 	memset(&client, 0, sizeof(client));
 	pthread_attr_init(&attr);
+	atomic_set(&client.dns_server_num, 0);
 
 	epollfd = epoll_create1(EPOLL_CLOEXEC);
 	if (epollfd < 0) {
diff --git a/src/dns_client.h b/src/dns_client.h
index 24238ac..0ffa5af 100644
--- a/src/dns_client.h
+++ b/src/dns_client.h
@@ -32,4 +32,6 @@ int dns_add_server(char *server_ip, int port, dns_server_type_t server_type);
 /* remove remote dns server */
 int dns_remove_server(char *server_ip, int port, dns_server_type_t server_type);
 
+int dns_server_num(void);
+
 #endif
diff --git a/src/dns_server.c b/src/dns_server.c
index a1b0ac6..54f45fd 100644
--- a/src/dns_server.c
+++ b/src/dns_server.c
@@ -550,7 +550,7 @@ static int _dns_server_process_answer(struct dns_request *request, char *domain,
 				}
 
 				if (addr[0] == 0 || addr[0] == 127) {
-					if (atomic_inc_return(&request->adblock) <= 1) {
+					if (atomic_inc_return(&request->adblock) <= dns_server_num() / 2) {
 						_dns_server_request_release(request);
 						break;
 					}