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From: "Tony Finch" <dot@dotat.at>
CC: "Tony Finch" <dot@dotat.at>
Subject: conflicting zones make catz crash
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From dot@dotat.at  Wed Sep  6 22:09:43 2017
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I was trying an experiment to see what happens if I have an explicitly
configured zone which is also listed in a catalog zone.

e.g. initial config snippet

	catalog-zones {
		zone "catz.arpa.cam.ac.uk"
			zone-directory "/zs";
	};

	zone catz.arpa.cam.ac.uk {
		type slave;
		file "/zs/catz.arpa.cam.ac.uk";
                masters { ucam; };
	};

The catz has an entry for 10.in-addr.arpa. I add the following to
named.conf

	zone 10.in-addr.arpa {
		type master;
		file "/zm/ten";
		allow-query { cudn; };
	};

then `rndc reconfig` says

rndc: 'reconfig' failed: already exists

and named logs:

2017-09-06.22:55:55.573 config: error: /etc/named.conf:202: zone '30.172.in-addr.arpa' already exists
2017-09-06.22:55:55.573 general: error: reloading configuration failed: already exists

OK, I delete the zone 10 configuration clause, and run `rndc reconfig`
again. named logs up to:

2017-09-06.22:56:04.490 general: info: automatic empty zone: view rec: EMPTY.AS112.ARPA
2017-09-06.22:56:04.490 config: warning: /etc/named.conf:192: catz: catalog zone 'catz.arpa.cam.ac.uk' will not be reconfigured

then crashes :-(


The wider question is what should happen when there is a conflict like
this. For instance, we also act as a secondary for Imperial College, so it
would be handy to use a catalog zone to do that. But I don't want to have
to trust them not to break our servers by adding a cam.ac.uk zone.

So ideally, I think explicitly configured zones should override / shadow
zones listed in a catalog. And if there are multiple catalog zones, there
should have a priority order so that zones listed in a higher priority
catalog will override / shadow zones in a lower priority catalog.


Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/  -  I xn--zr8h punycode
Biscay: Westerly or northwesterly 3 or 4, occasionally 5 in north. Moderate,
occasionally rough in north. Mainly fair. Good.