On Sun, Nov 27, 2016 at 6:10 AM Mukund Sivaraman <[email protected]> wrote:
> Hi Warren > > On Mon, Nov 14, 2016 at 02:05:31PM +0900, Warren Kumari wrote: > > Hi all, > > > > I have just submitted "Stretching DNS TTLs" > > (draft-wkumari-dnsop-ttl-stretching-00). > > > > The very high level overview is: > > If you are doing something like HAMMER / pre-fetch, and cannot reach > > the authoritative server when trying to refresh a record, you may > > continue to use a record past the TTL. > > This is working on the theory that stale bread is better than no bread. > > This is a strawman doc / idea, I'm expecting much discussion on if the > > above is true. > > Apparently, there are a couple of approaches that implementations have > taken: > > (1) In a proprietary patch for BIND: > - named as resolver first checks cache for a non-stale/unexpired answer > > - If no answer is found, named performs resolution, and it has to send > one or more fetches (query to an authoritative server) > > - If the fetch takes more than a threshold time (but not as long as the > timeout duration), named then serves any stale answer in the > cache. But named keeps the fetch going until it times out. If the > fetch eventually succeeds, the cache is updated. > > - A stale cache entry is not used beyond a particular maximum time. > Dear all, I'd like to apologize for not having responded (onlist) until now - this was not me ignoring you, rather we were getting our ducks in a row... David Lawrence and I have been chatting since Seoul - he is the author of the above patch; I'm planning on abandoning draft-wkumari-dnsop-ttl-stretching and he and I will (soon) be releasing a joint document which describes the behavior in his patch. This will be describing running code, and so will / should be closer to ready for publication. > (2) In a feature implemented for Unbound: > > - Unbound first checks cache > > - If a stale answer is found, its TTL is set to 0, and the cache entry > is served > > - If a stale answer is found, Unbound starts something similar to > prefetch/HAMMER. > > > NOTE: I believe that there may be (non-Google) IP associated with > > this. A lawyer will be filing the IPR disclosure later today (time > > zone differences, etc). > > The two approaches are somewhat different, and so at least one of them > may not be covered by this patent. > Yup. The IPR disclose was about IPR belonging to Xerocole. Xerocole was acquired by Akamai in March 2015. I believe that David will discuss the IPR with his employer. W > > Mukund >
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