diff --git a/octodns/manager.py b/octodns/manager.py
index f9542aa..e84b6f6 100644
--- a/octodns/manager.py
+++ b/octodns/manager.py
@@ -102,6 +102,8 @@ class Manager(object):
         plan = p[1]
         return len(plan.changes[0].record.zone.name) if plan.changes else 0
 
+    # TODO: all of this should get broken up, mainly so that it's not so huge
+    # and each bit can be cleanly tested independently
     def __init__(self, config_file, max_workers=None, include_meta=False):
         version = self._try_version('octodns', version=__VERSION__)
         self.log.info(
diff --git a/tests/test_octodns_manager.py b/tests/test_octodns_manager.py
index ab987d2..e22931a 100644
--- a/tests/test_octodns_manager.py
+++ b/tests/test_octodns_manager.py
@@ -712,6 +712,34 @@ class TestManager(TestCase):
             ),
         )
 
+    def test_subzone_handling(self):
+        manager = Manager(get_config_filename('simple.yaml'))
+
+        manager.config['zones'] = {
+            'unit.tests.': {},
+            'sub.unit.tests.': {},
+            'another.sub.unit.tests.': {},
+            'skipped.alevel.unit.tests.': {},
+        }
+
+        self.assertEqual(
+            {'unit.tests': {'skipped.alevel': {}, 'sub': {'another': {}}}},
+            manager.zone_tree,
+        )
+        self.assertEqual(
+            {'sub', 'skipped.alevel'},
+            manager.configured_sub_zones('unit.tests.'),
+        )
+        self.assertEqual(
+            {'another'}, manager.configured_sub_zones('sub.unit.tests.')
+        )
+        self.assertEqual(
+            set(), manager.configured_sub_zones('another.unit.tests.')
+        )
+        self.assertEqual(
+            set(), manager.configured_sub_zones('skipped.alevel.unit.tests.')
+        )
+
 
 class TestMainThreadExecutor(TestCase):
     def test_success(self):