Add check for IPv6 aswell

subnet.py

@@ -13,5 +13,16 @@ def zone_is_subset(re2o_reverse_zone, network):
     >>> zone_is_subset(zone, net1)
     True
     """
+    
+    if network.version == 4:
         return all(ipaddress.ip_network(n).subnet_of(network) for n in
-            zone["cidrs"])
+                re2o_reverse_zone["cidrs"])
+    
+    elif network.version == 6:
+        if re2o_reverse_zone["prefix_v6"]:
+            ipv6_prefix = re2o_reverse_zone["prefix_v6"] 
+            ipv6_prefix_length = re2o_reverse_zone["prefix_v6_length"]
+            net6 = ipaddress.ip_network(f"{ipv6_prefix}/{ipv6_prefix_length}")
+            return net6.subnet_of(network)
+        else:
+            return False