diff --git a/xCAT-server/sbin/xcatd b/xCAT-server/sbin/xcatd
index 185184b02..e595a27b6 100644
--- a/xCAT-server/sbin/xcatd
+++ b/xCAT-server/sbin/xcatd
@@ -378,6 +378,11 @@ sub do_installm_service {
         } else {
             ($client_name,$client_aliases) = gethostbyaddr($conn->peeraddr,AF_INET);
         }
+        unless ($client_name) {
+            my $myaddr = inet_ntoa($conn->peeraddr);
+            xCAT::MsgUtils->message("S","xcatd received a connection request from unknown host with ip address $myaddr, please check whether the reverse name resolution works correctly. The connection request will be ignored");
+            print "xcatd received a connection request from unknown host with ip address $myaddr, please check whether the reverse name resolution works correctly. The connection request will be ignored\n";
+        }
 
         $clients[0] = $client_name;
         if ($client_aliases) {
@@ -404,7 +409,11 @@ sub do_installm_service {
             if ($node) {  # Means the source isn't valid
                 $validclient=1;
                 last;
+            } else {
+                xCAT::MsgUtils->message("S","xcatd received a connection request from $client, which can not be found in xCAT nodelist table. The connection request will be ignored");
+                print "xcatd received a connection request from $client, which can not be found in xCAT nodelist table. The connection request will be ignored\n";
             }
+            
         }
 
         unless ($validclient) {
diff --git a/xCAT/postscripts/updateflag.awk b/xCAT/postscripts/updateflag.awk
index 66fbc9ebf..035a73e2c 100755
--- a/xCAT/postscripts/updateflag.awk
+++ b/xCAT/postscripts/updateflag.awk
@@ -6,27 +6,32 @@ BEGIN {
     xcatdport = ARGV[2]
     flag = ARGV[3]
     
-	if (!flag) flag = "next"
+    if (!flag) flag = "next"
 
-	ns = "/inet/tcp/0/" ARGV[1] "/" xcatdport
+    ns = "/inet/tcp/0/" ARGV[1] "/" xcatdport
 
-	while(1) {
-		if((ns |& getline) > 0)
-			print $0 | "logger -t xcat -p local4.info"
+    loop = 0
+    while(1) {
+        if((ns |& getline) > 0)
+            print $0 | "logger -t xcat -p local4.info"
         else {
             print "Retrying flag update" | "logger -t xcat -p local4.info"
             close(ns)
             system("sleep 10")
-        }
+            loop = loop + 1
+        }   
 
-		if($0 == "ready")
-			print flag |& ns
-		if($0 == "done")
-			break
-	}
+        if($0 == "ready")
+            print flag |& ns
+        if($0 == "done")
+            break
+        if(loop > 10) 
+            print "flag update failed" | "logger -t xcat -p local4.info"
+            break
+    }
 
-	close(ns)
+    close(ns)
 
-	exit 0
+    exit 0
 }