shorten sync response freshness
diff --git a/include/sync-logic.h b/include/sync-logic.h
index 49cc625..551cb06 100644
--- a/include/sync-logic.h
+++ b/include/sync-logic.h
@@ -188,7 +188,7 @@
   static const int m_syncInterestReexpress = 10; // seconds
   // don't forget to adjust value in SyncCcnxWrapper
 #else
-  static const int m_syncResponseFreshness = 2000;
+  static const int m_syncResponseFreshness = 4;
   static const int m_syncInterestReexpress = 4;
 #endif