[dns-operations] More Aggressive prefetch for popular names

Davey Song songlinjian at gmail.com
Mon Apr 8 02:03:06 UTC 2019

> The "popular sites" you mention have all done this already. They also
> tend to use services like Akamai, which use short TTLs, dynamic records,
> and CDNs which limit the types of damage that you are describing.
> I missed one case in the "outage of popular names during the TTL ". It is
that the short DNS TTL of CDN ,5 minutes for example, will be occasionally
ignored and changed by resolver operators up to 2-3  hours due to some
policy conflicts. It occurred one or twice in a month observed in one large
CDN operator I'm familiar with.  I'm not sure how Akamai or Cloudflare
handle this, but it happens every month, people are suffering.

It is partially due to different interest of recursive/authoritative
operators and loosely coordination between them as people mentioned. But I
also observed that resolver operators have motivation and tools to set
policy of a minimum TTL or a larger TTL . They care more about  the rate
of  cache miss than rate of serving stale data. Normally they are
cooperative if they receive a call and notice the conflicts for specific
names case by case, but there seems no automatic approach set before the
event between resolver and authoritative operators.

We have to get out of the mindset that it's our job to fix someone
> else's mistakes.

Mistakes of both resolver and authoritaive servers are observed. I'm
writing this not asking to add more straw on the camel. I just would like
to konw any best practice on this issue on this mailing list. Or it is
nothing but other people's problem?

Best regards,
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