North American Network Operators Group

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Re: dns authority changes and lame servers

  • From: Mike Lewinski
  • Date: Thu Oct 18 16:51:58 2007

Justin Scott wrote:

I suppose the problem with having an official list to query would be
getting all of the various registries to participate and keep it
regularly updated.  I personally qualify this as a slight inconvenience,
but I'm not sure I would call it a flaw in the DNS system.

If we just call DNS a distributed database, then it is easy to see that when the keys (glue at root) get updated, the relations to those keys *should* all reflect that change. The flaw is that the system creates cruft almost continuously. I'd love to see a graph of the cruft on a global scale, because I'm positive that over time it is growing (though in ways that are not always operationally impactful since most of it will be dead and abandoned zones still sitting in our named.conf).

And I'll admit, I'm not sure how to properly fix it either. My first thought was a BIND directive to "expire-stale-zones <interval>;" so that every <interval> the server might check to be sure it is still auth, and if it has found authority changed, would stop giving out AAs for it. But I see all kinds of operational issues arising from that too (such as, how do we gracefully setup new customer's zone before it has transitioned here).

Really, in my ideal Internet, once my server was notified that it was no longer authoritative, it would have an option to do a reverse xfer to the new auth servers (who would then be free to accept/reject the old information as necessary - can't count the number of times I've tried to get customers to provide zone file records in advance and failed because they don't know how/where to get them from). But that's an ideal Internet that will never exist, I know.