Phorm and Cookies

[James Firth]

> > I know this is analogous to HTTP caching but
> > caching is defined in the HTTP protocol and not in DNS.
> 
> I don't quite follow: caching is inherent to DNS.  I think you mean
> _transparent_ caching, but my memory is that isn't defined by an RFC
> for HTTP either.
> 
> ian

Transparent caching ensures byte-for-byte equivalence with the expected
response from the server.

I believe but have not checked that HTTP caching, including transparent
caching, is covered by RFC 2616.  Importantly the HTTP protocol defines the
VIA header, which I believe is still set by transparent proxies.

DNS is a completely different story.  I would argue that the end user
chooses their provider for a DNS services.  

If an ISP does chose to cache a DNS request, it at least has an obligation
to relay the requested information from the requested source and not attempt
to answer on behalf of the requested source using a different source of
information.

James Firth