diff --git a/DnsServerCore/Dns/Zone.cs b/DnsServerCore/Dns/Zone.cs
index c57e88c7..837a0535 100644
--- a/DnsServerCore/Dns/Zone.cs
+++ b/DnsServerCore/Dns/Zone.cs
@@ -204,7 +204,7 @@ namespace DnsServerCore.Dns
             }
 
             foreach (Zone subDomain in subDomainsToDelete)
-                currentZone._zones.TryRemove(subDomain._zoneLabel, out Zone deletedValue);
+                currentZone._zones.TryRemove(subDomain._zoneLabel, out _);
 
             return (currentZone._zones.Count == 0);
         }
@@ -384,6 +384,9 @@ namespace DnsServerCore.Dns
                 }
             }
 
+            if (_authoritativeZone && (type == DnsResourceRecordType.CNAME) && _entries.ContainsKey(DnsResourceRecordType.SOA))
+                throw new DnsServerException("Cannot add CNAME record to zone root.");
+
             _entries.AddOrUpdate(type, records, delegate (DnsResourceRecordType key, DnsResourceRecord[] existingValues)
             {
                 return records;