diff --git a/ReadMe.md b/ReadMe.md
index 743c643..f75e30d 100644
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -631,7 +631,7 @@ entware|ipkg update<br />ipkg install smartdns|软件源路径：<https://bin.en
 | serve-expired-ttl | 过期缓存服务最长超时时间 | 0 | 秒，0 表示停用超时，大于 0 表示指定的超时的秒数 | serve-expired-ttl 0 |
 | serve-expired-reply-ttl | 回应的过期缓存 TTL | 5 | 秒，0 表示停用超时，大于 0 表示指定的超时的秒数 | serve-expired-reply-ttl 30 |
 | dualstack-ip-selection | 双栈 IP 优选 | yes | [yes\|no] | dualstack-ip-selection yes |
-| dualstack-ip-selection-threshold | 双栈 IP 优选阈值 | 15ms | 单位为毫秒（ms） | dualstack-ip-selection-threshold [0-1000] |
+| dualstack-ip-selection-threshold | 双栈 IP 优选阈值 | 10ms | 单位为毫秒（ms） | dualstack-ip-selection-threshold [0-1000] |
 | user | 进程运行用户 | root | user [username] | user nobody |
 | ca-file | 证书文件 | /etc/ssl/<br />certs/ca-certificates.crt | 合法路径字符串 | ca-file /etc/ssl/certs/ca-certificates.crt |
 | ca-path | 证书文件路径 | /etc/ssl/certs | 合法路径字符串 | ca-path /etc/ssl/certs |
diff --git a/ReadMe_en.md b/ReadMe_en.md
index cd18345..f06970e 100644
--- a/ReadMe_en.md
+++ b/ReadMe_en.md
@@ -595,7 +595,7 @@ Note: Merlin firmware is derived from ASUS firmware and can theoretically be use
 |serve-expired-ttl|Cache serve expired limit TTL|0|second, 0: disable, > 0  seconds after expiration|serve-expired-ttl 0
 |serve-expired-reply-ttl|TTL value to use when replying with expired data|5|second, 0: disable, > 0  seconds after expiration|serve-expired-reply-ttl 30
 |dualstack-ip-selection|Dualstack ip selection|yes|[yes\|no]|dualstack-ip-selection yes
-|dualstack-ip-selection-threshold|Dualstack ip select thresholds|15ms|millisecond|dualstack-ip-selection-threshold [0-1000]
+|dualstack-ip-selection-threshold|Dualstack ip select thresholds|10ms|millisecond|dualstack-ip-selection-threshold [0-1000]
 |user|run as user|root|user [username]|user nobody
 |ca-file|certificate file|/etc/ssl/certs/<br />ca-certificates.crt|path|ca-file /etc/ssl/certs/ca-certificates.crt
 |ca-path|certificates path|/etc/ssl/certs|path|ca-path /etc/ssl/certs
diff --git a/src/dns_conf.c b/src/dns_conf.c
index af4e823..307562b 100644
--- a/src/dns_conf.c
+++ b/src/dns_conf.c
@@ -132,7 +132,7 @@ struct dns_conf_address_rule dns_conf_address_rule;
 /* dual-stack selection */
 int dns_conf_dualstack_ip_selection = 1;
 int dns_conf_dualstack_ip_allow_force_AAAA;
-int dns_conf_dualstack_ip_selection_threshold = 15;
+int dns_conf_dualstack_ip_selection_threshold = 10;
 
 /* TTL */
 int dns_conf_rr_ttl;
diff --git a/src/fast_ping.c b/src/fast_ping.c
index 0cabbe1..6d70938 100644
--- a/src/fast_ping.c
+++ b/src/fast_ping.c
@@ -329,10 +329,6 @@ static struct addrinfo *_fast_ping_getaddr(const char *host, const char *port, i
 	struct addrinfo hints;
 	struct addrinfo *result = NULL;
 	int errcode = 0;
-	
-	if (host == NULL || port == NULL) {
-		goto errout;
-	}
 
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_family = AF_UNSPEC;
@@ -340,7 +336,8 @@ static struct addrinfo *_fast_ping_getaddr(const char *host, const char *port, i
 	hints.ai_protocol = protocol;
 	errcode = getaddrinfo(host, port, &hints, &result);
 	if (errcode != 0) {
-		tlog(TLOG_ERROR, "get addr info failed. host:%s, port: %s, error %s\n", host, port, gai_strerror(errcode));
+		tlog(TLOG_ERROR, "get addr info failed. host:%s, port: %s, error %s\n", host != NULL ? host : "",
+			 port != NULL ? port : "", gai_strerror(errcode));
 		goto errout;
 	}