IS-04-01 test_12 dependency? 
Test 12 in the Node API suite checks that there are no 'ver_' TXT records in registered operation.

But obviously this relies on a Registry being enabled, which as far as we can see isn't ensured by this test itself, so it's only likely to pass currently if run sufficiently soon after one of the tests that does. 

Should it do something similar to `test_21` do you think, @andrewbonney?

We'd like to make `do_registry_basics_prereqs` wait for a bit after the last registry is disabled (like it does after all the others) in order to make `test_21` reliable, but that will make `test_12` always fail right now.
diff --git a/IS0401Test.py b/IS0401Test.py
index 161160c..3d63446 100644
--- a/IS0401Test.py
+++ b/IS0401Test.py
@@ -39,6 +39,7 @@ class IS0401Test(GenericTest):
         self.dns_server = dns_server
         self.node_url = self.apis[NODE_API_KEY]["url"]
         self.registry_basics_done = False
+        self.registry_basics_data = []
         self.is04_utils = IS04Utils(self.node_url)
         self.zc = None
         self.zc_listener = None
@@ -83,7 +84,7 @@ class IS0401Test(GenericTest):
             registry_mdns = []
             priority = 0
             for registry in self.registries:
-                info = self._registry_mdns_info(registry.get_port(), priority)
+                info = self._registry_mdns_info(registry.get_data().port, priority)
                 registry_mdns.append(info)
                 priority += 10
 
@@ -106,9 +107,9 @@ class IS0401Test(GenericTest):
             time.sleep(1)
 
         # Ensure we have two heartbeats from the Node, assuming any are arriving (for test_05)
-        if len(self.registries[0].get_heartbeats()) > 0:
+        if len(self.registries[0].get_data().heartbeats) > 0:
             # It is heartbeating, but we don't have enough of them yet
-            while len(self.registries[0].get_heartbeats()) < 2:
+            while len(self.registries[0].get_data().heartbeats) < 2:
                 time.sleep(1)
 
             # Once registered, advertise all other registries at different (ascending) priorities
@@ -126,12 +127,12 @@ class IS0401Test(GenericTest):
                     break
 
                 heartbeat_countdown = HEARTBEAT_INTERVAL + 1
-                while len(self.registries[index + 1].get_heartbeats()) < 1 and heartbeat_countdown > 0:
+                while len(self.registries[index + 1].get_data().heartbeats) < 1 and heartbeat_countdown > 0:
                     # Wait until the heartbeat interval has elapsed or a heartbeat has been received
                     time.sleep(1)
                     heartbeat_countdown -= 1
 
-                if len(self.registries[index + 1].get_heartbeats()) < 1:
+                if len(self.registries[index + 1].get_data().heartbeats) < 1:
                     # Testing has failed at this point, so we might as well abort
                     break
 
@@ -142,6 +143,8 @@ class IS0401Test(GenericTest):
             registry.disable()
 
         self.registry_basics_done = True
+        for registry in self.registries:
+            self.registry_basics_data.append(registry.get_data())
 
     def test_01(self, test):
         """Node can discover network registration service via multicast DNS"""
@@ -152,8 +155,8 @@ class IS0401Test(GenericTest):
 
         self.do_registry_basics_prereqs()
 
-        registry = self.registries[0]
-        if len(registry.get_post_data()) > 0:
+        registry_data = self.registry_basics_data[0]
+        if len(registry_data.posts) > 0:
             return test.PASS()
 
         return test.FAIL("Node did not attempt to register with the advertised registry.")
@@ -167,8 +170,8 @@ class IS0401Test(GenericTest):
 
         self.do_registry_basics_prereqs()
 
-        registry = self.registries[0]
-        if len(registry.get_post_data()) > 0:
+        registry_data = self.registry_basics_data[0]
+        if len(registry_data.posts) > 0:
             return test.PASS()
 
         return test.FAIL("Node did not attempt to register with the advertised registry.")
@@ -181,11 +184,11 @@ class IS0401Test(GenericTest):
 
         self.do_registry_basics_prereqs()
 
-        registry = self.registries[0]
-        if len(registry.get_post_data()) == 0:
+        registry_data = self.registry_basics_data[0]
+        if len(registry_data.posts) == 0:
             return test.FAIL("No registrations found")
 
-        for resource in registry.get_post_data():
+        for resource in registry_data.posts:
             if "Content-Type" not in resource[1]["headers"]:
                 return test.FAIL("Node failed to signal its Content-Type correctly when registering.")
             elif resource[1]["headers"]["Content-Type"] != "application/json":
@@ -197,8 +200,8 @@ class IS0401Test(GenericTest):
         found_resource = None
         if ENABLE_DNS_SD:
             # Look up data in local mock registry
-            registry = self.registries[0]
-            for resource in registry.get_post_data():
+            registry_data = self.registry_basics_data[0]
+            for resource in registry_data.posts:
                 if resource[1]["payload"]["type"] == res_type and resource[1]["payload"]["data"]["id"] == res_id:
                     found_resource = resource[1]["payload"]["data"]
         else:
@@ -271,14 +274,14 @@ class IS0401Test(GenericTest):
 
         self.do_registry_basics_prereqs()
 
-        registry = self.registries[0]
-        if len(registry.get_heartbeats()) < 2:
+        registry_data = self.registry_basics_data[0]
+        if len(registry_data.heartbeats) < 2:
             return test.FAIL("Not enough heartbeats were made in the time period.")
 
-        initial_node = registry.get_post_data()[0]
+        initial_node = registry_data.posts[0]
 
         last_hb = None
-        for heartbeat in registry.get_heartbeats():
+        for heartbeat in registry_data.heartbeats:
             # Ensure the Node ID for heartbeats matches the registrations
             if heartbeat[1]["node_id"] != initial_node[1]["payload"]["data"]["id"]:
                 return test.FAIL("Heartbeats matched a different Node ID to the initial registration.")
@@ -355,9 +358,32 @@ class IS0401Test(GenericTest):
         """Node advertises a Node type mDNS announcement with no ver_* TXT records
         in the presence of a Registration API"""
 
+        if not ENABLE_DNS_SD:
+            return test.DISABLED("This test cannot be performed when ENABLE_DNS_SD is False")
+
+        registry = self.registries[0]
+        registry_info = self._registry_mdns_info(registry.get_data().port, 0)
+
+        # Reset the registry to clear previous data, although we won't be checking it
+        registry.reset()
+        registry.enable()
+
+        if DNS_SD_MODE == "multicast":
+            # Advertise a registry at pri 0 and allow the Node to do a basic registration
+            self.zc.register_service(registry_info)
+
+        # Wait for n seconds after advertising the service for the first POST from a Node
+        time.sleep(DNS_SD_ADVERT_TIMEOUT)
+
         browser = ServiceBrowser(self.zc, "_nmos-node._tcp.local.", self.zc_listener)
         time.sleep(1)
         node_list = self.zc_listener.get_service_list()
+
+        # Withdraw the registry advertisement now we've performed a browse for Node advertisements
+        if DNS_SD_MODE == "multicast":
+            self.zc.unregister_service(registry_info)
+        registry.disable()
+
         for node in node_list:
             address = socket.inet_ntoa(node.address)
             port = node.port
@@ -486,20 +512,20 @@ class IS0401Test(GenericTest):
 
         last_hb = None
         last_registry = None
-        for registry in self.registries:
-            if len(registry.get_heartbeats()) < 1:
+        for registry_data in self.registry_basics_data:
+            if len(registry_data.heartbeats) < 1:
                 return test.FAIL("Node never made contact with registry advertised on port {}"
-                                 .format(registry.get_port()))
+                                 .format(registry_data.port))
 
-            first_hb_to_registry = registry.get_heartbeats()[0]
+            first_hb_to_registry = registry_data.heartbeats[0]
             if last_hb:
                 if first_hb_to_registry < last_hb:
                     return test.FAIL("Node sent a heartbeat to the registry on port {} before the registry on port {}, "
                                      "despite their priorities requiring the opposite behaviour"
-                                     .format(registry.get_port(), last_registry.get_port()))
+                                     .format(registry_data.port, last_registry.port))
 
             last_hb = first_hb_to_registry
-            last_registry = registry
+            last_registry = registry_data
 
         return test.PASS()
 
@@ -511,12 +537,12 @@ class IS0401Test(GenericTest):
 
         self.do_registry_basics_prereqs()
 
-        for index, registry in enumerate(self.registries):
-            if len(registry.get_heartbeats()) < 1:
+        for index, registry_data in enumerate(self.registry_basics_data):
+            if len(registry_data.heartbeats) < 1:
                 return test.FAIL("Node never made contact with registry advertised on port {}"
-                                 .format(registry.get_port()))
+                                 .format(registry_data.port))
 
-            if index > 0 and len(registry.get_post_data()) > 0:
+            if index > 0 and len(registry_data.posts) > 0:
                 return test.FAIL("Node re-registered its resources when it failed over to a new registry, when it "
                                  "should only have issued a heartbeat")
 
@@ -697,7 +723,7 @@ class IS0401Test(GenericTest):
             return test.DISABLED("This test cannot be performed when ENABLE_DNS_SD is False")
 
         registry = self.registries[0]
-        registry_info = self._registry_mdns_info(registry.get_port(), 0)
+        registry_info = self._registry_mdns_info(registry.get_data().port, 0)
 
         # Reset the registry to clear previous heartbeats, and enable in 200 test mode
         registry.reset()
@@ -723,13 +749,13 @@ class IS0401Test(GenericTest):
                 # Check that a POST and DELETE match the Node's ID
                 node_id = r.json()["id"]
                 found_post = False
-                for resource in registry.get_post_data():
+                for resource in registry.get_data().posts:
                     if resource[1]["payload"]["type"] == "node" and resource[1]["payload"]["data"]["id"] == node_id:
                         found_post = True
                 if not found_post:
                     return test.FAIL("Node did not attempt to make contact with the registry")
                 found_delete = False
-                for resource in registry.get_delete_data():
+                for resource in registry.get_data().deletes:
                     if resource[1]["type"] == "node" and resource[1]["id"] == node_id:
                         found_delete = True
                 if not found_delete:
diff --git a/Registry.py b/Registry.py
index 4a582d7..9e085ad 100644
--- a/Registry.py
+++ b/Registry.py
@@ -26,6 +26,14 @@ class RegistryCommon(object):
         self.resources = {"node": {}}
 
 
+class RegistryData(object):
+    def __init__(self, port):
+        self.port = port
+        self.posts = []
+        self.deletes = []
+        self.heartbeats = []
+
+
 class Registry(object):
     def __init__(self, data_store, port_increment):
         self.common = data_store
@@ -35,16 +43,14 @@ class Registry(object):
     def reset(self):
         self.last_time = time.time()
         self.last_hb_time = 0
-        self.post_data = []
-        self.delete_data = []
+        self.data = RegistryData(self.port)
         self.common.reset()
-        self.heartbeats = []
         self.enabled = False
         self.test_first_reg = False
 
     def add(self, headers, payload):
         self.last_time = time.time()
-        self.post_data.append((self.last_time, {"headers": headers, "payload": payload}))
+        self.data.posts.append((self.last_time, {"headers": headers, "payload": payload}))
         if "type" in payload and "data" in payload:
             if payload["type"] not in self.common.resources:
                 self.common.resources[payload["type"]] = {}
@@ -53,26 +59,17 @@ class Registry(object):
 
     def delete(self, headers, payload, resource_type, resource_id):
         self.last_time = time.time()
-        self.delete_data.append((self.last_time, {"headers": headers, "payload": payload, "type": resource_type,
-                                                  "id": resource_id}))
+        self.data.deletes.append((self.last_time, {"headers": headers, "payload": payload, "type": resource_type,
+                                                   "id": resource_id}))
         if resource_type in self.common.resources:
             self.common.resources[resource_type].pop(resource_id, None)
 
     def heartbeat(self, headers, payload, node_id):
         self.last_hb_time = time.time()
-        self.heartbeats.append((self.last_hb_time, {"headers": headers, "payload": payload, "node_id": node_id}))
-
-    def get_post_data(self):
-        return self.post_data
-
-    def get_delete_data(self):
-        return self.delete_data
-
-    def get_heartbeats(self):
-        return self.heartbeats
+        self.data.heartbeats.append((self.last_hb_time, {"headers": headers, "payload": payload, "node_id": node_id}))
 
-    def get_port(self):
-        return self.port
+    def get_data(self):
+        return self.data
 
     def get_resources(self):
         return self.common.resources
['IS0401Test.py', 'Registry.py']