[dnsdist] Rule for lowering the TTL for a specific qname with qtype TXT

[Tom]

Hi Otto

I was able to do this with addResponseAction like this:

addResponseAction(
   AndRule({
     RegexRule("^_acme-challenge\\."),
     QTypeRule(DNSQType.TXT),
     RCodeRule(DNSRCode.NXDOMAIN)
   }),
   LimitTTLResponseAction(10,10,{6})
)


Thanks for giving me the right hint,
Tom


On 9/23/25 07:40, Otto Moerbeek via dnsdist wrote:
> Hello
> 
> and AndRule is one possible approach, but if you use a packet cache,
> you can also set maxNegativeTTL. This TTL will be used then for all
> NXDomain or NoData answers.
> See https://www.dnsdist.org/reference/config.html#packetcache
> 
> And AndRule would look like
> 
> addResponseAction(AndRule{...}, ...)
> 
> 	-Otto
> 
> On Tue, Sep 23, 2025 at 07:14:36AM +0200, Tom via dnsdist wrote:
> 
>> Hi list
>>
>> I'm struggling with implementing the following dnsdist rule/behavior:
>> If...
>> a) qname starts with "_acme-challenge" AND
>> b) qtype is TXT AND
>> c) RCODE is NXDOMAIN
>> then
>> lower the response TTL to 30s.
>>
>> What's the best way to achieve this? With a LUA rule or perhaps with
>> "addAction(AndRule..."?
>>
>> Thanks in advance for any hints.
>> Tom
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