diff --git a/conf/create_opendkim_key.conf.sample b/conf/create_opendkim_key.conf.sample
index 82f8ff5..1cdb5c6 100644
--- a/conf/create_opendkim_key.conf.sample
+++ b/conf/create_opendkim_key.conf.sample
@@ -6,6 +6,15 @@
 # ----------
 # DNS Server
 # ----------
+
+# - dns_main_zone_master_server
+# -
+# - if main zone (for which a DKIM key should be created) isn't already registered, then 
+# - try this nameserver.
+# -
+# - This requires that the name servers are already set up.
+# -
+#dns_main_zone_master_server=
  
 # - dns_dkim_zone_master_server
 # -