4880. [bug] Named wasn't returning the target of a cross zone

CNAME between to served zones when recursion was
                        desired and available (RD=1, RA=1). Don't return
                        the CNAME target otherwise to prevent accidental
                        cache poisoning. [RT #47078]

bin/tests/system/auth/ns1/example.net.db

@@ -0,0 +1,17 @@
+; Copyright (C) 2018  Internet Systems Consortium, Inc. ("ISC")
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+$TTL 300        ; 5 minutes
+@                       IN SOA  ns root (
+				2018010100 ; serial
+				1800       ; refresh (30 minutes)
+				1800       ; retry (30 minutes)
+				1814400    ; expire (3 weeks)
+				3600       ; minimum (1 hour)
+				)
+			NS      ns
+ns                      A       10.53.0.1
+server			A	10.53.0.100