diff --git a/Replication.md b/Replication.md
index d732d93..9582dea 100644
--- a/Replication.md
+++ b/Replication.md
@@ -7,7 +7,7 @@ Basically, the way it works is:
 1. start weed master, and optionally specify the default replication type
 
    ```bash
-   ./weed master -defaultReplication=001
+   ./weed master -defaultReplication=001 # 001 means for each file a replica will be created in the same rack
    ```
 
 2. start volume servers as this: