diff --git a/weed/command/master.go b/weed/command/master.go
index 40d9b9a16..82e33bae1 100644
--- a/weed/command/master.go
+++ b/weed/command/master.go
@@ -48,7 +48,7 @@ type MasterOptions struct {
 func init() {
 	cmdMaster.Run = runMaster // break init cycle
 	m.port = cmdMaster.Flag.Int("port", 9333, "http listen port")
-	m.ip = cmdMaster.Flag.String("ip", util.DetectedHostAddress(), "master <ip>|<server> address")
+	m.ip = cmdMaster.Flag.String("ip", util.DetectedHostAddress(), "master <ip>|<server> address, also used as identifier")
 	m.ipBind = cmdMaster.Flag.String("ip.bind", "", "ip address to bind to")
 	m.metaFolder = cmdMaster.Flag.String("mdir", os.TempDir(), "data directory to store meta data")
 	m.peers = cmdMaster.Flag.String("peers", "", "all master nodes in comma separated ip:port list, example: 127.0.0.1:9093,127.0.0.1:9094,127.0.0.1:9095")
diff --git a/weed/command/server.go b/weed/command/server.go
index a9e1c94bb..7b184a329 100644
--- a/weed/command/server.go
+++ b/weed/command/server.go
@@ -49,7 +49,7 @@ var cmdServer = &Command{
 }
 
 var (
-	serverIp                  = cmdServer.Flag.String("ip", util.DetectedHostAddress(), "ip or server name")
+	serverIp                  = cmdServer.Flag.String("ip", util.DetectedHostAddress(), "ip or server name, also used as identifier")
 	serverBindIp              = cmdServer.Flag.String("ip.bind", "", "ip address to bind to")
 	serverTimeout             = cmdServer.Flag.Int("idleTimeout", 30, "connection idle seconds")
 	serverDataCenter          = cmdServer.Flag.String("dataCenter", "", "current volume server's data center name")
diff --git a/weed/command/volume.go b/weed/command/volume.go
index 0e8224dbc..7fd31665f 100644
--- a/weed/command/volume.go
+++ b/weed/command/volume.go
@@ -69,7 +69,7 @@ func init() {
 	cmdVolume.Run = runVolume // break init cycle
 	v.port = cmdVolume.Flag.Int("port", 8080, "http listen port")
 	v.publicPort = cmdVolume.Flag.Int("port.public", 0, "port opened to public")
-	v.ip = cmdVolume.Flag.String("ip", util.DetectedHostAddress(), "ip or server name")
+	v.ip = cmdVolume.Flag.String("ip", util.DetectedHostAddress(), "ip or server name, also used as identifier")
 	v.publicUrl = cmdVolume.Flag.String("publicUrl", "", "Publicly accessible address")
 	v.bindIp = cmdVolume.Flag.String("ip.bind", "", "ip address to bind to")
 	v.masters = cmdVolume.Flag.String("mserver", "localhost:9333", "comma-separated master servers")