[dns-operations] prefetching and thundering herds

Mark Delany b9w at charlie.emu.st
Wed Jul 15 12:10:16 UTC 2020


On 15Jul20, Tony Finch allegedly wrote:
> I've been wondering about the effects of stub resolvers with caches as
> clients of recursive servers. To what extent do they cause a thundering
> herd effect where all the cache entries expire with the same deadline?

I'm not sure how a stub cache could make things worse.

Queries passed thru to the recursive server can never be more frequent
or have different arrival rates than if the stub doesn't cache at all,
can they?

IOWs, isn't a stub cache just short-circuiting some queries which
might otherwise end up at the recursive server? The stub's not moving
queries in time is it?

Or are you thinking of an aggressive stub which re-populates on its
own initiative? That I imagine could create a thundering herd
scenario.


Mark.


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