On Fri, 10 Aug 2007, Max Inux wrote:

Of course the CDN wouldn't know or care, it would however possibly lead to that user experiencing negative performance or availability outside the realm of the CDN's control. I know where we are we move things via dns atleast 2xTTL early, usually more, but emergency situations (i.e. taiwan earthquake, fiber cuts, oc192 outages etc.) would have serious negative implications for users or servers ignoring the TTL- it is sometimes set for a legitimate reason.

I'm sorry, I think you or I miscommunicated... What I was asking, as 'how does the CDN or CDN operator know that the recursive server is ignoring the TTL returned with the RR as opposed to client side issues?' Your response didn't really answer that part. I ask because you seem to have data proving ( to some extent ) that 'many nameservers ignore ttls', I was curious how you'd gathered that, and how you'd know that the nameservers (aside from querying them directly) were ignoring TTLs on RRs. Thanks.

On Aug 10, 2007, at 6:22 PM, Chris L. Morrow wrote:

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On Aug 10, 2007, at 9:13 AM, Max Inux wrote:

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Working for a content delivery network I can tell you that there are many nameservers ignoring TTL that affect many users (AOL being the largest american one). Coincidentally AOL users aren't

So, I'd also ask this, do you know it's the recursive server, or is the behavior that you see related more to the application caching and not respecting the TTL? (IE for instance and it's default 30 minute, I think, ttl).

How does a CDN tell the recursive server is doing this vice the client app?