[dns-operations] TTL=0

[Greg Choules]

Hi Fred.
No, I am not talking about dscacheutil or any particular client software. I
just want to know whether, in the opinion of the world's DNS professionals,
recursive servers should or shouldn't ever send answers from cache with
TTL=0.

cheers, Greg

On Thu, 17 Jan 2019 at 23:15, m3047 <m3047 at m3047.net> wrote:

> Who cares about the RFC? In practice, SOME caching resolvers (and that's
> being charitable) WILL answer with TTL=0. I've had to live with PFSense
> deployments which did this.
>
> Which in turn leads to things like (for Mac users):
>
>    dscacheutil -flushcache
>
> Is that what you're talking about?
>
> On Thu, 17 Jan 2019, Greg Choules wrote:
> > [...]
> >
> > Is there ever a case, for cached answers, that the recursive server would
> > answer the client with TTL=0? Or would that be illegal? RFC1034 states
> that
> > records with TTL=0 "should not be cached". Note "should" and not "must".
>
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