diff --git a/src/dns_client.c b/src/dns_client.c
index 03771b3..07f14df 100644
--- a/src/dns_client.c
+++ b/src/dns_client.c
@@ -115,6 +115,7 @@ struct dns_server_info {
 	/* client socket */
 	int fd;
 	int ttl;
+	int ttl_range;
 	SSL *ssl;
 	SSL_CTX *ssl_ctx;
 	dns_server_status status;
@@ -270,6 +271,7 @@ int _dns_client_server_add(char *server_ip, struct addrinfo *gai, dns_server_typ
 	server_info->status = DNS_SERVER_STATUS_INIT;
 	server_info->result_flag = result_flag;
 	server_info->ttl = ttl;
+	server_info->ttl_range = 0;
 
 	if (gai->ai_addrlen > sizeof(server_info->in6)) {
 		tlog(TLOG_ERROR, "addr len invalid, %d, %zd, %d", gai->ai_addrlen, sizeof(server_info->addr), server_info->ai_family);
@@ -278,12 +280,16 @@ int _dns_client_server_add(char *server_ip, struct addrinfo *gai, dns_server_typ
 	memcpy(&server_info->addr, gai->ai_addr, gai->ai_addrlen);
 
 	/* start ping task */
-	if (ttl == 0 && (result_flag & DNSSERVER_FLAG_CHECK_TTL)) {
+	if (ttl <= 0 && (result_flag & DNSSERVER_FLAG_CHECK_TTL)) {
 		server_info->ping_host = fast_ping_start(PING_TYPE_DNS, server_ip, 0, 60000, 1000, _dns_client_server_update_ttl, server_info);
 		if (server_info->ping_host == NULL) {
 			tlog(TLOG_ERROR, "start ping failed.");
 			goto errout;
 		}
+
+		if (ttl < 0) {
+			server_info->ttl_range = -ttl;
+		}
 	}
 
 	/* add to list */
@@ -940,8 +946,10 @@ static int _dns_client_process_udp(struct dns_server_info *server_info, struct e
 	tlog(TLOG_DEBUG, "recv udp, from %s, len: %d, ttl: %d", gethost_by_addr(from_host, (struct sockaddr *)&from, from_len), len, ttl);
 
 	if ((ttl != server_info->ttl) && (server_info->ttl > 0) && (server_info->result_flag & DNSSERVER_FLAG_CHECK_TTL)) {
-		/* tlog(TLOG_DEBUG, "TTL mismatch, from:%d, local %d, discard result", ttl, server_info->ttl); */
-		return 0;
+		if ((ttl < server_info->ttl - server_info->ttl_range) || (ttl > server_info->ttl + server_info->ttl_range)) {
+			/* tlog(TLOG_DEBUG, "TTL mismatch, from:%d, local %d, discard result", ttl, server_info->ttl); */
+			return 0;
+		}
 	}
 
 	time(&server_info->last_recv);
diff --git a/src/dns_conf.c b/src/dns_conf.c
index b7a99f9..c5e60f6 100644
--- a/src/dns_conf.c
+++ b/src/dns_conf.c
@@ -92,7 +92,7 @@ int config_server(int argc, char *argv[], dns_server_type_t type, int default_po
 			}
 
 			ttl = atoi(optarg);
-			if (ttl < 0 || ttl > 255) {
+			if (ttl < -255 || ttl > 255) {
 				tlog(TLOG_ERROR, "ttl value is invalid.");
 				return -1;
 			}
diff --git a/src/dns_server.c b/src/dns_server.c
index 990e414..b247627 100644
--- a/src/dns_server.c
+++ b/src/dns_server.c
@@ -185,13 +185,15 @@ static void _dns_server_audit_log(struct dns_request *request)
 		return;
 	}
 
-	if (request->qtype == DNS_T_AAAA) {
+	if (request->qtype == DNS_T_AAAA && request->has_ipv6) {
 		snprintf(req_result, sizeof(req_result), "%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x", request->ipv6_addr[0],
 				 request->ipv6_addr[1], request->ipv6_addr[2], request->ipv6_addr[3], request->ipv6_addr[4], request->ipv6_addr[5], request->ipv6_addr[6],
 				 request->ipv6_addr[7], request->ipv6_addr[8], request->ipv6_addr[9], request->ipv6_addr[10], request->ipv6_addr[11], request->ipv6_addr[12],
 				 request->ipv6_addr[13], request->ipv6_addr[14], request->ipv6_addr[15]);
-	} else if (request->qtype == DNS_T_A) {
+	} else if (request->qtype == DNS_T_A && request->has_ipv4) {
 		snprintf(req_result, sizeof(req_result), "%d.%d.%d.%d", request->ipv4_addr[0], request->ipv4_addr[1], request->ipv4_addr[2], request->ipv4_addr[3]);
+	} else if (request->has_soa) {
+		return;
 	} else {
 		return;
 	}
@@ -508,10 +510,10 @@ int _dns_server_request_complete(struct dns_request *request)
 	}
 
 	if (request->qtype == DNS_T_A) {
-		tlog(TLOG_INFO, "result: %s, rcode: %d,  %d.%d.%d.%d\n", request->domain, request->rcode, request->ipv4_addr[0], request->ipv4_addr[1],
-			 request->ipv4_addr[2], request->ipv4_addr[3]);
-
 		if (request->has_ipv4) {
+			tlog(TLOG_INFO, "result: %s, rcode: %d,  %d.%d.%d.%d\n", request->domain, request->rcode, request->ipv4_addr[0], request->ipv4_addr[1],
+				request->ipv4_addr[2], request->ipv4_addr[3]);
+
 			if (request->has_ping_result == 0 && request->ttl_v4 > DNS_SERVER_TMOUT_TTL) {
 				request->ttl_v4 = DNS_SERVER_TMOUT_TTL;
 			}
@@ -524,12 +526,10 @@ int _dns_server_request_complete(struct dns_request *request)
 		}
 
 	} else if (request->qtype == DNS_T_AAAA) {
-		tlog(TLOG_INFO, "result: %s, rcode: %d,  %.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x", request->domain, request->rcode,
-			 request->ipv6_addr[0], request->ipv6_addr[1], request->ipv6_addr[2], request->ipv6_addr[3], request->ipv6_addr[4], request->ipv6_addr[5],
-			 request->ipv6_addr[6], request->ipv6_addr[7], request->ipv6_addr[8], request->ipv6_addr[9], request->ipv6_addr[10], request->ipv6_addr[11],
-			 request->ipv6_addr[12], request->ipv6_addr[13], request->ipv6_addr[14], request->ipv6_addr[15]);
-
 		if (request->has_ipv4) {
+			tlog(TLOG_INFO, "result: %s, rcode: %d,  %d.%d.%d.%d\n", request->domain, request->rcode, request->ipv4_addr[0], request->ipv4_addr[1],
+				request->ipv4_addr[2], request->ipv4_addr[3]);
+
 			dns_cache_insert(request->domain, cname, cname_ttl, request->ttl_v4, DNS_T_AAAA, request->ipv4_addr, DNS_RR_A_LEN);
 
 			if (((request->ping_ttl_v4 + (dns_conf_dualstack_ip_selection_threshold * 10) < request->ping_ttl_v6) && (request->ping_ttl_v4 > 0)) ||
@@ -540,6 +540,11 @@ int _dns_server_request_complete(struct dns_request *request)
 		}
 
 		if (request->has_ipv6) {
+			tlog(TLOG_INFO, "result: %s, rcode: %d,  %.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x", request->domain, request->rcode,
+			 request->ipv6_addr[0], request->ipv6_addr[1], request->ipv6_addr[2], request->ipv6_addr[3], request->ipv6_addr[4], request->ipv6_addr[5],
+			 request->ipv6_addr[6], request->ipv6_addr[7], request->ipv6_addr[8], request->ipv6_addr[9], request->ipv6_addr[10], request->ipv6_addr[11],
+			 request->ipv6_addr[12], request->ipv6_addr[13], request->ipv6_addr[14], request->ipv6_addr[15]);
+
 			if (request->has_ping_result == 0 && request->ttl_v6 > DNS_SERVER_TMOUT_TTL) {
 				request->ttl_v6 = DNS_SERVER_TMOUT_TTL;
 			}
@@ -556,6 +561,10 @@ int _dns_server_request_complete(struct dns_request *request)
 		return 0;
 	}
 
+	if (request->has_soa) {
+		tlog(TLOG_INFO, "result: %s, qtype: %d, SOA", request->domain, request->qtype);
+	}
+
 	_dns_setup_ipset(request);
 	_dns_reply(request);