[dns-operations] Who Ignores TTLs ?

Joseph S D Yao jsdy at tux.org
Fri Feb 18 23:02:29 UTC 2011

On Thu, Feb 17, 2011 at 07:38:37AM +0100, bert hubert wrote:
> On Thu, Feb 17, 2011 at 03:01:17PM +1300, Simon Lyall wrote:
> > I keep seeing a persistent complaint that some DNS caching operators
> > ignore TTLs or otherwise keep records for longer than the TTL would
> > indicate.
> I am aware of a severely resource constrained PowerDNS operator once
> patching their Recursor to set a lower bound on their TTLs of 5 or 10
> minutes.
> But this is probably not on the scale of what you mean.

I could see where an upper bound would help a storage-constrained
server.  And it's allowed by RFC 2181:

    Implementations are always free to place an upper bound on any TTL
    received, and treat any larger values as if they were that upper
    bound.  The TTL specifies a maximum time to live, not a mandatory
    time to live.

** Joe Yao				jsdy at tux.org - Joseph S. D. Yao

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