diff --git a/bind9vm/docker-compose.yml b/bind9vm/docker-compose.yml
index a0fdadf..e706c34 100644
--- a/bind9vm/docker-compose.yml
+++ b/bind9vm/docker-compose.yml
@@ -1,3 +1,5 @@
+# version to run on secondary server, possibly virtual
+
 services:
     bind9:
         container_name: bind9