diff --git a/perl-xCAT/xCAT/Usage.pm b/perl-xCAT/xCAT/Usage.pm
index d30b9edd2..2ef132eb3 100755
--- a/perl-xCAT/xCAT/Usage.pm
+++ b/perl-xCAT/xCAT/Usage.pm
@@ -289,7 +289,7 @@ my %usage = (
              [-u] [--range IPranges][-t tries][--vpdtable][-C counts][-T timeout]",
     "switchdiscover" =>
 "Usage: switchdiscover [-h|--help|-v|--version]
-       switchdiscover [<noderange>|--range ipranges] [-s scan_methods] [-r|-x|-z][-n] [-w] [-V|--verbose]",
+       switchdiscover [<noderange>|--range ipranges] [-s scan_methods] [-r|-x|-z] [-w] [-V|--verbose]",
   "rflash" =>
 "Usage: 
     rflash [ -h|--help|-v|--version]
diff --git a/xCAT-client/pods/man1/switchdiscover.1.pod b/xCAT-client/pods/man1/switchdiscover.1.pod
index af17fd3e1..301b049f4 100755
--- a/xCAT-client/pods/man1/switchdiscover.1.pod
+++ b/xCAT-client/pods/man1/switchdiscover.1.pod
@@ -11,7 +11,7 @@ I<switchdiscover [-h| --help]>
 I<switchdiscover [-v| --version]>
 
 
-I<switchdiscover [noderange|--range ip_ranges] [-V] [-w][-r|-x|-z][-n][-s scan_methods]>
+I<switchdiscover [noderange|--range ip_ranges] [-V] [-w][-r|-x|-z][-s scan_methods]>
 
 
 
@@ -32,8 +32,6 @@ B<noderange>   The switches which the user want to discover.
 
 B<-h>          Display usage message.
 
-B<-n>          Only display and write the newly discovered switches.
-
 B<--range>     Specify one or more IP ranges.  
             It accepts multiple formats. For example, 192.168.1.1/24, 40-41.1-2.3-4.1-100.
             If the range is huge, for example, 192.168.1.1/8, switchdiscover may take a very long 
@@ -42,7 +40,7 @@ B<--range>     Specify one or more IP ranges.
 B<-r>          Display Raw response.
 
 B<-s>          It is a comma separated list of methods for switch discovery. 
-            The possible switch scan methods are: llpd, nmap and snmp. The default is lldpd.
+            The possible switch scan methods are: lldpd, nmap and snmp. The default is lldpd.
 
 B<-v>          Command Version.
 
diff --git a/xCAT-server/lib/xcat/plugins/switchdiscover.pm b/xCAT-server/lib/xcat/plugins/switchdiscover.pm
index a70b92061..ec6575145 100755
--- a/xCAT-server/lib/xcat/plugins/switchdiscover.pm
+++ b/xCAT-server/lib/xcat/plugins/switchdiscover.pm
@@ -547,9 +547,9 @@ sub nmap_scan {
     # us the ip addresses of the nodes. If none is define, use the
     # subnets for all the interfaces.
     ##################################################
-	my $ranges = get_ip_ranges($request);
+    my $ranges = get_ip_ranges($request);
 
-	$ccmd = "/usr/bin/nmap -sn -oX - @$ranges";
+    $ccmd = "/usr/bin/nmap -sn -oX - @$ranges";
     print $ccmd;
     my $result = xCAT::Utils->runcmd($ccmd, 0);
     if ($::RUNCMD_RC != 0)
@@ -633,8 +633,8 @@ sub snmp_scan {
       ip  :  IP address passed by the switch after scan
     Returns:
       hose:  hostname of the switch
-      if host is empty, format hostname as switch and ip combination
-         ex:  switch-9-114-5-6
+      if host is empty, try to lookup use ip address, otherwise format hostname 
+      as switch and ip combination. ex:  switch-9-114-5-6
 =cut
 #--------------------------------------------------------------------------------
 sub get_hostname {
@@ -642,9 +642,12 @@ sub get_hostname {
     my $ip = shift;
 
     if ( !$host ) {
-        my $ip_str = $ip;
-        $ip_str =~ s/\./\-/g;
-        $host = "switch-$ip_str";
+        $host = gethostbyaddr( inet_aton($ip), AF_INET );
+        if ( !$host ) {
+            my $ip_str = $ip;
+            $ip_str =~ s/\./\-/g;
+            $host = "switch-$ip_str";
+        }
     }
     return $host;
 }