diff --git a/EduNetworkBuilder/IPAddressEntry.cs b/EduNetworkBuilder/IPAddressEntry.cs
index a9100cb..b2ded60 100644
--- a/EduNetworkBuilder/IPAddressEntry.cs
+++ b/EduNetworkBuilder/IPAddressEntry.cs
@@ -249,9 +249,11 @@ namespace EduNetworkBuilder
             {
                 tIPAddress = mynet.DNSLookup(ParentDevice, tbIPAddress.Text);                    
             }
-            if(tIPAddress != null)
+            if (tIPAddress != null)   //device name used, convert to IP address and netmask
             {
                 taddress = tIPAddress.GetIP;
+                if (DHCPInterface == null)
+                    tbNetmask.Text = tIPAddress.GetMaskString;
             }
             else
                 taddress = tbIPAddress.Text.ParseIp();