Ray Bellis wrote:

On 04/11/2018 08:05, Ray Bellis wrote:

AFAIK, BIND does not currently do this.  That said, MarkA has a patch
that supports it, so we do know it's possible.

Correction - BIND *does* do this, but only for address records that are
already in the cache. If the AAAA for the target is in the cache, but
the A record isn't, that's all you'll get.

that's all we need. it's all we do for MX and NS additional data, too.

Mark's patch forces BIND to pre-fill the cache with the A and AAAA
records for the SRV target before replying.

that would be a mistake. we are hitting for average here not power -- the behaviour to optimize for is whatever's most common. if the SRV is used, the AAAA or A RRsets will be fetched, and thus cached. if the SRV is only used once, that caching effort will be wasted. if the SRV is used many times, then the dominant use case will be that the additional data is found in cache because the client caused this to be so.

P Vixie

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