Re: [RRG] Generic requirements on mapping mechanisms

[Scott Brim <swb@employees.org>]

Excerpts from Tony Li on Tue, Mar 11, 2008 05:34:21PM -0400:
> > In the case of the DNS, some of the cost of using short TTLs is
> > supported by the owner of the domain names with a short TTL. The
> > resolvers of nodes that resolve those domain names also suffer
> > some cost, but the nodes that do not contact these domain names do
> > not suffer the additional cost. In this case, there is some cost
> > (replying to more DNS requests) for the domain that chooses to use
> > short lifetime. This is not perfect since the resolvers that
> > contact this domain also support some cost.
> 
> OK.  I thought perhaps you had a way of removing even that cost.
> 
> One way of shifting that cost further is for the advertising site to
> proactively issue updates based on historical requests.
> 
> Tony

Are you suggesting that if the advertising site does this, the caching
site could toss out cache entries more casually, because they are
likely to be refreshed?  I wonder if proactive updates will increase
both the cost of caching and the cost of processing updates even more,
because updates will be sent and processed even when they are not
needed.

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