diff --git a/src/client/WFDnsClient.cc b/src/client/WFDnsClient.cc
index 151ac910..2e4ec3ed 100644
--- a/src/client/WFDnsClient.cc
+++ b/src/client/WFDnsClient.cc
@@ -100,7 +100,7 @@ struct DnsStatus
 	size_t next_server;			// next server to try
 	size_t last_server;			// last server to try
 	size_t next_domain;			// next search domain to try
-	int attempt_left;
+	int attempts_left;
 	int try_origin_state;
 };
 
@@ -163,8 +163,8 @@ static void __callback_internal(WFDnsTask *task, const DnsParams& params,
 	if (try_next_server)
 	{
 		if (s.last_server == s.next_server)
-			s.attempt_left--;
-		if (s.attempt_left <= 0)
+			s.attempts_left--;
+		if (s.attempts_left <= 0)
 			return;
 
 		s.next_server = (s.next_server + 1) % p->uris.size();
@@ -247,7 +247,7 @@ WFDnsTask *WFDnsClient::create_dns_task(const std::string& name,
 
 	status.origin_name = name;
 	status.next_domain = 0;
-	status.attempt_left = p->attempts;
+	status.attempts_left = p->attempts;
 	status.try_origin_state = DNS_STATUS_TRY_ORIGIN_FIRST;
 
 	if (!name.empty() && name.back() == '.')
diff --git a/src/manager/DnsCache.h b/src/manager/DnsCache.h
index fa719dae..0ccf081e 100644
--- a/src/manager/DnsCache.h
+++ b/src/manager/DnsCache.h
@@ -27,6 +27,7 @@
 #include <mutex>
 #include <utility>
 #include "LRUCache.h"
+#include "DnsUtil.h"
 
 #define GET_TYPE_TTL		0
 #define GET_TYPE_CONFIDENT	1
@@ -38,15 +39,6 @@ struct DnsCacheValue
 	int64_t expire_time;
 };
 
-class ValueDeleter
-{
-public:
-	void operator() (const DnsCacheValue& value) const
-	{
-		freeaddrinfo(value.addrinfo);
-	}
-};
-
 // RAII: NO. Release handle by user
 // Thread safety: YES
 // MUST call release when handle no longer used
@@ -56,6 +48,20 @@ public:
 	using HostPort = std::pair<std::string, unsigned short>;
 	using DnsHandle = LRUHandle<HostPort, DnsCacheValue>;
 
+	class ValueDeleter
+	{
+	public:
+		void operator() (const DnsCacheValue& value) const
+		{
+			struct addrinfo *ai = value.addrinfo;
+
+			if (ai && (ai->ai_flags | AI_PASSIVE))
+				freeaddrinfo(ai);
+			else
+				DnsUtil::freeaddrinfo(ai);
+		}
+	};
+
 public:
 	// release handle by get/put
 	void release(DnsHandle *handle)
diff --git a/src/manager/WFGlobal.cc b/src/manager/WFGlobal.cc
index ca3f7c19..5f727445 100644
--- a/src/manager/WFGlobal.cc
+++ b/src/manager/WFGlobal.cc
@@ -627,7 +627,8 @@ static inline const char *__try_options(const char *p, const char *q,
 	return NULL;
 }
 
-static void __set_options(const char *p, int& ndots, int& attempt, bool& rotate)
+static void __set_options(const char *p,
+						  int *ndots, int *attempts, bool *rotate)
 {
 	const char *start;
 	const char *opt;
@@ -648,17 +649,17 @@ static void __set_options(const char *p, int& ndots, int& attempt, bool& rotate)
 			break;
 
 		if ((opt = __try_options(start, p, "ndots:")) != NULL)
-			ndots = atoi(opt);
+			*ndots = atoi(opt);
 		else if ((opt = __try_options(start, p, "attempts:")) != NULL)
-			attempt = atoi(opt);
+			*attempts = atoi(opt);
 		else if ((opt = __try_options(start, p, "rotate")) != NULL)
-			rotate = true;
+			*rotate = true;
 	}
 }
 
 static int __parse_resolv_conf(const char *filename,
 							   std::string& url, std::string& search_list,
-							   int& ndots, int& attempts, bool& rotate)
+							   int *ndots, int *attempts, bool *rotate)
 {
 	size_t bufsize = 0;
 	void *line = NULL;
@@ -713,8 +714,8 @@ private:
 			std::string search;
 
 			client = new WFDnsClient;
-			if (__parse_resolv_conf(path, url, search, ndots, attempts,
-									rotate) >= 0)
+			if (__parse_resolv_conf(path, url, search, &ndots, &attempts,
+									&rotate) >= 0)
 			{
 				if (client->init(url, search, ndots, attempts, rotate) >= 0)
 					return;
diff --git a/src/nameservice/WFDnsResolver.cc b/src/nameservice/WFDnsResolver.cc
index 6ec137f9..bf9cb374 100644
--- a/src/nameservice/WFDnsResolver.cc
+++ b/src/nameservice/WFDnsResolver.cc
@@ -238,6 +238,16 @@ static int __readaddrinfo(const char *filename,
 	return ret < 0 ? EAI_SYSTEM : EAI_NONAME;
 }
 
+// Add AI_PASSIVE to point that this addrinfo is alloced by getaddrinfo
+static void __add_passive_flags(struct addrinfo *ai)
+{
+	while (ai)
+	{
+		ai->ai_flags |= AI_PASSIVE;
+		ai = ai->ai_next;
+	}
+}
+
 static ThreadDnsTask *__create_thread_dns_task(const std::string& host,
 											   unsigned short port,
 											   thread_dns_callback_t callback)
@@ -277,7 +287,7 @@ public:
 private:
 	virtual void dispatch();
 	virtual SubTask *done();
-	void dns_callback(ThreadDnsTask *dns_task);
+	void thread_dns_callback(ThreadDnsTask *dns_task);
 	void dns_single_callback(WFDnsTask *dns_task);
 	void dns_parallel_callback(const ParallelWork *pwork);
 	void dns_callback_internal(DnsOutput *dns_task,
@@ -373,6 +383,7 @@ void WFResolverTask::dispatch()
 
 			dns_in.reset(host_, port_);
 			DnsRoutine::run(&dns_in, &dns_out);
+			__add_passive_flags((struct addrinfo *)dns_out.get_addrinfo());
 			dns_callback_internal(&dns_out, (unsigned int)-1, (unsigned int)-1);
 			insert_dns_ = false;
 		}
@@ -391,6 +402,7 @@ void WFResolverTask::dispatch()
 		{
 			DnsOutput out;
 			DnsRoutine::create(&out, ret, ai);
+			__add_passive_flags((struct addrinfo *)out.get_addrinfo());
 			dns_callback_internal(&out, dns_ttl_default_, dns_ttl_min_);
 			insert_dns_ = false;
 		}
@@ -398,7 +410,7 @@ void WFResolverTask::dispatch()
 
 	if (insert_dns_ && !client)
 	{
-		auto&& cb = std::bind(&WFResolverTask::dns_callback,
+		auto&& cb = std::bind(&WFResolverTask::thread_dns_callback,
 							  this,
 							  std::placeholders::_1);
 		ThreadDnsTask *dns_task = __create_thread_dns_task(host_, port_,
@@ -595,10 +607,14 @@ void WFResolverTask::dns_parallel_callback(const ParallelWork *pwork)
 	delete this;
 }
 
-void WFResolverTask::dns_callback(ThreadDnsTask *dns_task)
+void WFResolverTask::thread_dns_callback(ThreadDnsTask *dns_task)
 {
 	if (dns_task->get_state() == WFT_STATE_SUCCESS)
-		dns_callback_internal(dns_task->get_output(), dns_ttl_default_, dns_ttl_min_);
+	{
+		DnsOutput *out = dns_task->get_output();
+		__add_passive_flags((struct addrinfo *)out->get_addrinfo());
+		dns_callback_internal(out, dns_ttl_default_, dns_ttl_min_);
+	}
 	else
 	{
 		this->state = dns_task->get_state();
diff --git a/src/protocol/DnsUtil.cc b/src/protocol/DnsUtil.cc
index f34ac51b..7faf9c32 100644
--- a/src/protocol/DnsUtil.cc
+++ b/src/protocol/DnsUtil.cc
@@ -124,3 +124,16 @@ int DnsUtil::getaddrinfo(const protocol::DnsResponse *resp,
 
 	return 0;
 }
+
+void DnsUtil::freeaddrinfo(struct addrinfo *ai)
+{
+	struct addrinfo *p;
+
+	while (ai != NULL)
+	{
+		p = ai;
+		ai = ai->ai_next;
+		free(p->ai_canonname);
+		free(p);
+	}
+}
diff --git a/src/protocol/DnsUtil.h b/src/protocol/DnsUtil.h
index 4fa696a4..08def0fb 100644
--- a/src/protocol/DnsUtil.h
+++ b/src/protocol/DnsUtil.h
@@ -32,6 +32,7 @@ public:
 	static int getaddrinfo(const protocol::DnsResponse *resp,
 						   unsigned short port,
 						   struct addrinfo **res);
+	static void freeaddrinfo(struct addrinfo *ai);
 };
 
 class DnsResultCursor