[nsd-users] on axfr fallback

[Shane Kerr]

Ondrej,

On Wed, 2008-11-12 at 23:45 +0100, Ondřej Surý wrote:
> I don't have time to do test, so I am going to ask.  What error code does
> bind returns if you delete it's journal (and ixfr-from-differences is yes)?
> Ie. if bind cannot provide IXFR, only AXFR?  Will nsd fallback to AXFR in
> that case?  (I hope the answer is that it's the FORMATERR error code ;)).

If BIND cannot provide IXFR then it automatically falls back to AXFR.

I think this behavior is badly broken, but it is allowed by the RFC.
(There are several scenarios which can cause BIND to not have enough
information to provide IXFR from any particular serial, which means if
you are unlucky enough to try that server before a server that *can*
provide IXFR, you have to transfer the entire zone.)

--
Shane