diff --git a/net/test/test.cpp b/net/test/test.cpp
index a61d6f72..ad182a06 100644
--- a/net/test/test.cpp
+++ b/net/test/test.cpp
@@ -714,9 +714,9 @@ TEST(utils, resolver) {
     DEFER(delete resolver);
     net::IPAddr localhost("127.0.0.1");
     net::IPAddr addr = resolver->resolve("localhost");
-    EXPECT_EQ(localhost.to_nl(), addr.to_nl());
+    if (addr.is_ipv4()) EXPECT_EQ(localhost.to_nl(), addr.to_nl());
     auto func = [&](net::IPAddr addr_){
-        EXPECT_EQ(localhost.to_nl(), addr_.to_nl());
+        if (addr_.is_ipv4()) EXPECT_EQ(localhost.to_nl(), addr_.to_nl());
     };
     resolver->resolve("localhost", func);
     resolver->discard_cache("non-exist-host.com");
diff --git a/net/utils.cpp b/net/utils.cpp
index efbe1bac..ad9209d8 100644
--- a/net/utils.cpp
+++ b/net/utils.cpp
@@ -260,7 +260,12 @@ class DefaultResolver : public Resolver {
 public:
     DefaultResolver(uint64_t cache_ttl, uint64_t resolve_timeout)
         : dnscache_(cache_ttl), resolve_timeout_(resolve_timeout) {}
-    ~DefaultResolver() { dnscache_.clear(); }
+    ~DefaultResolver() {
+        for (auto it : dnscache_) {
+            ((IPAddrList*)it->_obj)->delete_all();
+        }
+        dnscache_.clear();
+    }
 
     IPAddr resolve(const char *host) override {
         auto ctr = [&]() -> IPAddrList* {
@@ -287,10 +292,7 @@ class DefaultResolver : public Resolver {
         auto ips = dnscache_.borrow(host, ctr);
         if (ips->empty()) LOG_ERRNO_RETURN(0, IPAddr(), "Domain resolution for ` failed", host);
         auto ret = ips->front();
-        if (!ret->single()) {  // access in round robin order
-            auto front = ips->pop_front();
-            ips->push_back(front);
-        }
+        ips->node = ret->next();  // access in round robin order
         return ret->addr;
     }
 
@@ -300,9 +302,9 @@ class DefaultResolver : public Resolver {
         auto ipaddr = dnscache_.borrow(host);
         if (ip.undefined() || ipaddr->empty()) ipaddr.recycle(true);
         else {
-            for (auto it : *ipaddr) {
-                if (it->addr == ip) {
-                    ipaddr->erase(it);
+            for (auto itr = ipaddr->rbegin(); itr != ipaddr->rend(); itr++) {
+                if ((*itr)->addr == ip) {
+                    ipaddr->erase(*itr);
                     break;
                 }
             }
diff --git a/thread/list.h b/thread/list.h
index 435f8aa8..3f42a8de 100644
--- a/thread/list.h
+++ b/thread/list.h
@@ -221,6 +221,48 @@ class intrusive_list_node : public __intrusive_list_node
     {
         return {nullptr, nullptr};
     }
+
+    struct reverse_iterator
+    {
+        __intrusive_list_node* ptr;
+        __intrusive_list_node* end;
+        T* operator*()
+        {
+            return static_cast<T*>(ptr);
+        }
+        reverse_iterator& operator++()
+        {
+            ptr = ptr->__prev_ptr;
+            if (ptr == end)
+                ptr = nullptr;
+            return *this;
+        }
+        reverse_iterator operator++(int)
+        {
+            auto rst = *this;
+            ptr = ptr->__prev_ptr;
+            if (ptr == end)
+                ptr = nullptr;
+            return rst;
+        }
+        bool operator == (const reverse_iterator& rhs) const
+        {
+            return ptr == rhs.ptr;
+        }
+        bool operator != (const reverse_iterator& rhs) const
+        {
+            return !(*this == rhs);
+        }
+    };
+
+    reverse_iterator rbegin()
+    {
+        return {this->__prev_ptr, this->__prev_ptr};
+    }
+    reverse_iterator rend()
+    {
+        return {nullptr, nullptr};
+    }
 };
 
 
@@ -321,6 +363,7 @@ class intrusive_list
         return node == nullptr;
     }
     typedef typename NodeType::iterator iterator;
+    typedef typename NodeType::reverse_iterator reverse_iterator;
     iterator begin()
     {
         return node ? node->begin() : end();
@@ -329,6 +372,14 @@ class intrusive_list
     {
         return {nullptr, nullptr};
     }
+    reverse_iterator rbegin()
+    {
+        return node ? node->rbegin() : rend();
+    }
+    reverse_iterator rend()
+    {
+        return {nullptr, nullptr};
+    }
     intrusive_list split_front_inclusive(NodeType* ptr)
     {
         auto ret = node;