[Pdns-users] TTL ?

[Brian Candler]

On 17/10/2026 08:34, listy via Pdns-users wrote:
>
> I have zones whose TTL are 60s, to whose authoritative server PDNS 
> recursor forwards and when I a modify a record, that change is not 
> reflected, not refreshed in PDNS.
>
> What am I missing, must be something obvious since I ain't an expert 🙂 

It would be much easier to help you if you told us the actual zone name 
(if it's visible on the Internet): 
https://blog.powerdns.com/2016/01/18/open-source-support-out-in-the-open/

If it's not visible on the Internet, then show the entire contents of 
the zone (including its SOA and NS records) and the entire 
configurations of your recursor and auth server.

Zones don't have a TTL. The individual records within the zone have 
TTLs. The zone's SOA record has a "minimum" field which says how long a 
recursor can cache a negative answer.  It also has a "refresh" interval, 
but that only affects zone transfers, i.e. authoritative to 
authoritative. See https://en.wikipedia.org/wiki/SOA_record

To debug this, I suggest you query the record directly from the auth 
server, and also from the recursor: make sure you note both the answer 
and the TTL.

dig +norec @ip.of.pdns.auth some.rec.ord. a
dig @ip.of.pdns.recursor some.reco.ord. a

The TTL from the recursor should count downwards as it moves closer to 
expiry (as long as it's not a negative answer).

Then make a change in the authoritative server and repeat the tests.  
The query to the authoritative server should change immediately, the 
recursor should still return the old value while the TTL continues to 
count down. When it hits zero it will query the auth server again and 
should refresh.

This should help pin down the issue: is the TTL wrong from the auth 
server? Is the auth server not changing when you think it is? Is the 
recursor not forwarding to the auth server? Or is the problem that you 
get a negative answer initially, and then add the record to the auth 
server and the cache isn't showing it? Then you could be hitting the 
negative answer caching.

That's all I can give you as general advice, without seeing the actual 
zone and config.

HTH,

Brian.