[dns-operations] Who Ignores TTLs ?

George Michaelson ggm at apnic.net
Thu Feb 17 02:21:11 UTC 2011

At a presentation held by CNNIC during IETF, CNNIC demonstrated research s/w aimed at on-the-fly adjustment of TTL to enhance cache retention behaviours.

I have some concerns about the probity of this kind of change, and how it could work under DNSSEC, but I would say this is well beyond urban legend: some large DNS providers are actively considering playing with the DNS TTL in order to manage traffic flows.

I believe the intention is to mitigate ddos.


On 17/02/2011, at 12:01 PM, 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 suspect this might be an urban legend since most DNS caching software doesn't even offer this as an option last time I checked.
> Does anybody actually do this? Because it keep being brought up by some peopel as to why things like GSLB don't work.
> -- 
> Simon Lyall  |  Very Busy  |  Web: http://www.darkmere.gen.nz/
> "To stay awake all night adds a day to your life" - Stilgar | eMT.
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