Question about additional section in BIND-responses

[Matus UHLAR - fantomas]

>>>On Tue, Aug 16, 2022 at 05:28:19PM +0200, Tom wrote:
>>>>Using BIND-9.18.5 as a recursive server:
>>>>What's the reason, that BIND answers with the additional section for the
>>>>the following query where for example Knot resolver and also PowerDNS
>>>>resolver doesn't add the additional section for the same query?
>>>>
>>>>[...]
>>>>
>>>>Any hints why BIND adds the additional section while other resolvers
>>>>doesn't? Is there an option in BIND to behave like Knot/PDNS?

>>On 8/17/22 02:27, Evan Hunt wrote:
>>>The option is "minimal-responses".  If you set it to "yes", it will omit
>>>authority and additional section data except when necessary.
>>>
>>>The default is "no-auth-recursive", which omits authority section data
>>>when it isn't strictly necessary, but will still add additional data for
>>>records in the answer section.

>On 8/17/22 06:45, Tom wrote:
>>I've already set "minimal-responses yes;", but the additional 
>>section/data is still shown. So based on your explanation, BIND 
>>assumes, this data is necessary, why? And why behaves BIND different 
>>here than Knot/PDNS where no additional section is shown for the 
>>same query?

On 22.08.22 15:06, Tom wrote:
>Does an BIND expert has an idea or an explanation, why the additional 
>section is still shown, although "minimal-responses yes;" is set? And 
>why the additional section seems necessary for BIND and not for 
>example for Knot/PDNS for the same query?

ftp://ftp.isc.org/isc/bind9/9.18.5/doc/arm/html/reference.html#namedconf-statement-minimal-responses

yes: the server only adds records to the authority and additional sections 
when such records are required by the DNS protocol (for example, when 
returning delegations or negative responses).  This provides the best server 
performance but may result in more client queries.


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