diff --git a/src/ndns-enum.hpp b/src/ndns-enum.hpp
index be48bd1..39e77b0 100644
--- a/src/ndns-enum.hpp
+++ b/src/ndns-enum.hpp
@@ -40,6 +40,14 @@
 std::ostream&
 operator<<(std::ostream& os, const NdnsType ndnsType);
 
+/**
+ * @brief define Return code of Update's Response
+ */
+enum UpdateReturnCode {
+  UPDATE_OK = 0, ///< Update succeeds
+  UPDATE_FAILURE = 1 ///< Update fails
+};
+
 } // namespace ndns
 } // namespace ndn