Help: BIND _ Recursive query

[Matus UHLAR - fantomas]

>> >On 4 Mar 2019, at 16:20, Paul Kosinski wrote:
>> >> provides our users with general caching DNS service for
>> >> all other domains.
>> >
>> >[...]
>> >
>> >> Its "named.conf" file doesn't list any "forwarders" any more, and
>> >> "forward-only" is gone, but it still has a leftover "recursion yes"
>> >> clause. Am I correct is assuming that this is now useless and can
>> >> be removed?

>> On 04.03.19 16:33, Niall O'Reilly wrote:
>> >If you want "general caching DNS service" to continue to work,
>> >you'll need to keep "recursion yes".

>On Mon, 4 Mar 2019 19:30:36 +0100
>Matus UHLAR - fantomas <uhlar at fantomas.sk> wrote:
>> actually "recursion yes;" is the default, so if you remove it, it
>> stays set to yes (unless it's set to "no" somewhere).
>>
>> recursion is the feature that allows BIND to resolve domains not
>> configured locally, you surely need it enabled.

On 09.03.19 13:33, Paul Kosinski wrote:
>I gather "recursion yes" (explicit or default) controls whether BIND
>*does* recursion itself, in the sense of querying other DNS servers for
>data it doesn't have,

I believe that BIND does query other servers for data required for e.g. 
issuing notify messages, even if the recursion is disabled.

> not whether it *issues* queries with the
>"recursion desired" flag set. (Somewhat confusing terminology, in my
>opinion.)

AFAIK "stub" or "static-stub" domains are queried without recursion desired
(RD) flag set, but only if recursion is allowed.  Thus, RD flag is not
related to recursion status.

>So is the "recursion desired" flag only set when there are forwarders?
>Presumably it is set in the case of "forward only", but what happens if
>there are forwarders defined and both "recursion yes" (default) and
>"forward first" (default) are specified?

if there are forwarders defined, they are queried with RD flag set.
It doesn't matter if they are set globally or per-domain,
not if there's "forward first" or "forward only" set.

in the "recursion no" case, forwarders are not queried, only for cases I
mentioned above (like resolving nameservers to send notifies to them).

-- 
Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
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