A Cambridge Catalog Zone

2017-09-06 - News - Tony Finch

Catalog Zones are a new feature in BIND 9.11 which allow a econdary server to automatically configure itself using a specially-formatted zone. The isc.org knowledge base has an introduction to catalog zones and Jan-Piet Mens has some notes on his catalog zone tests.

We can use this new feature to make "stealth secondary" configurations much shorter and lower-maintenance. Accordingly, there is now a catz.arpa.cam.ac.uk catalog zone corresponding to our recommended stealth secondary configuration, and our sample BIND configuration has been updated with notes on how to use it.


This started off with some testing of the in-progress BIND 9.12 implementation of RFC 8198, which allows a validating DNSSEC resolver to use NSEC records to synthesize negative responses. (This spec is known as the Cheese Shop after an early draft which refers to a Monty Python sketch, https://tools.ietf.org/html/draft-wkumari-dnsop-cheese-shop / https://tools.ietf.org/html/rfc8198)

RFC 8198 is very effective at suppressing unnecessary queries especially to the root DNS servers and the upper levels of the reverse DNS. A large chunk of my DNS server configuration previously tried to help with that by adding a lot of locally-served empty zones (as specified by RFC 6761 etc.) With the cheese shop all that becomes redundant.

The other big chunk of my configuration is the stealth slave list. I have previously not investigated catalog-zones in detail, since they aren't quite expressive enough for use by our central DNS servers, and in any case their configuration is already automated. But it's just right for the stealth slave configuration on my test server (and ppsw, etc.)

Setting up a Cambridge catalog zone was not too difficult. Altogether it allowed me to delete over 100 zone configurations from my test server.