Minimum TTL?

sthaug at sthaug at
Fri Feb 9 06:02:19 UTC 2018

> I think what is "OK" is up to each administrator.
> Obviously the zone administrators have decided that they want people to 
> use the 2s TTL.
> That being said, it is up to each individual recursive server operator 
> if they want to honor what the zone administrators have published, or if 
> the recursive administrators want to override published desires.
> > It really is something for the zone owner to consider.
> Yes and no.  Yes it's up to the zone owner to consider what intentions 
> that they want to publish.  No, the zone owner has no influence on how I 
> operate my servers.  I choose how I operate my servers.

Yesterday I measured, on our busiest resolvers, the amount of replies
with TTL=0 the resolvers received (from the authoritative servers).
Turns out we receive around 2.3 percent replies with TTL=0. This is
a percentage I can live with, and I see no reason to artificially
inflate the TTL.

That being said - if the percentage had been significantly higher, I
would feel it was perfectly reasonable to set a minimum TTL of for
instance 10s. I agree that this is a decision for each operator.

Steinar Haug, Nethelp consulting, sthaug at

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