Cname + @ records caused bind failing to load

bin/v-add-dns-record

@@ -73,6 +73,10 @@ if [ "$rtype" != "CAA" ]; then
     fi
 fi
 
+if [ $record = "@" ] && [ $rtype = "CNAME" ]; then
+    check_result $E_INVALID "CNAME on root is not allowed"
+fi
+
 # Additional argument formatting
 format_domain
 format_domain_idn