Re: TTL From Parent or Child Zone?

On 17/02/2009, Matthew Dempsky <[email protected]> wrote:
> On Tue, Feb 17, 2009 at 2:18 PM, Sabahattin Gucukoglu
> <[email protected]> wrote:
>> Is djbdns likewise afflicted by this bug?
>
> dnscache always caches the latest RRset received from any nameserver
> that has authority for a given name.  If dnscache queries a parent
> server and receives an RRset, it will cache that; if later it talks to
> the child server and receives another RRset for the same name, it will
> update its cache with the new RRset; if it later talk to the parent
> server again and again receives another RRset for the same name, it
> will once again update the cache.

The data in the parent zone isn't authoritative.  If djbdns caches it,
it's wrong, IMHO.  It should discard additional data as fast as
possible in favour of genuine data from the authoritative servers.
This really means that as soon as you've learned the address of a name
server in additional data, you use it once and then throw the
additional data away.  You can keep the response from the master
server, of course; in the course of learning the answer to your
question you should now have genuinely authoritative additional data
about the authoritative name servers and their addresses and TTLs that
you can keep.

Cheers,
Sabahattin

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