Why two lookups for a CNAME?

[Reindl Harald]

Am 22.10.2015 um 17:41 schrieb Phil Mayers:
> On 22/10/15 16:37, Reindl Harald wrote:
>
>> since in a normal environment that don't matter consider in case of a
>> caching-only nameserver in such an environment using unbound instead of
>> named because it supports "cache-min-ttl" which is also strongly
>> recommended on a inbound mailserver using RBL's
>>
>> cache-min-ttl: 600
>> cache-max-ttl: 10800
>
> Right, but he'll still see a slow, expired-cache case every min-ttl
> won't he? Unless unbound does prefetch?

onbound *does* prefetch if enabled

https://www.unbound.net/documentation/unbound.conf.html

prefetch: <yes or no>
If yes, message cache elements are prefetched before they expire to 
keep  the  cache  up to date.  Default is no.  Turning it on gives about 
10 percent more traffic and load on the machine, but popular items do 
not expire from the cache

i like named for many reasons on authoritative nameservers, but for 
caching only unbound is way easier to maintain with more caching features

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