bind9/bin/tests/system/mirror

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This test checks whether zones configured with "type mirror;" behave as
expected.

ns1 is an authoritative-only server.  It only serves the root zone, which is
mirrored by ns3.

ns2 is an authoritative-only server.  It serves a number of zones, some of which
are delegated to it by ns1 and used in recursive resolution tests aimed at ns3
while others are only served so that ns3 has a primary server to mirror zones
from during various tests of the mirror zone implementation.

ns3 is a recursive resolver.  It has a number of mirror zones configured.  This
is the only server whose behavior is being examined by this system test.