diff --git a/octodns/manager.py b/octodns/manager.py
index d9e0180..7ee2057 100644
--- a/octodns/manager.py
+++ b/octodns/manager.py
@@ -338,6 +338,17 @@ class Manager(object):
         return kwargs
 
     def configured_sub_zones(self, zone_name):
+        '''
+        Accepts either UTF-8 or IDNA encoded zone name and returns the list of
+        any configured sub-zones in IDNA form. E.g. for the following
+        configured zones:
+          some.com.
+          other.some.com.
+          deep.thing.some.com.
+        It would return
+          other
+          deep.thing
+        '''
         if self._configured_sub_zones is None:
             # First time through we compute all the sub-zones