
What DNS Is Not - bensummers
http://queue.acm.org/detail.cfm?id=1647302
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bensummers
Part of me agrees with Vixie's horror at fundamental internet infrastructure
being abused for profit. Wildcarding to show adverts on mistyped addresses is
just evil.

But when the rules are broken slightly to give the user a better experience
which is consistent with their intent and expectations, such as CDNs, isn't
there room for a little innovation?

~~~
acdha
The question I'd ask is whether DNS is the right place for a CDN - in some
ways it seems like that should either happen at the routing level (e.g.
anycast) or at the application level (e.g. http redirects to user-appropriate
servers) depending on the service.

~~~
bensummers
HTTP redirects would introduce a delay and quite a bit of additional traffic.
However, application level choice of server embedded in the output HTML would
be efficient, and more accurate because it knows the precise IP address of the
client, not merely the DNS server it's using.

But this requires much more than just changing a URL, it requires logic on the
CDN customer's servers and some form of replication of the database mapping IP
address to server.

So you're right, DNS is not the right place for a CDN. But it works. It's just
like web browsers are completely the wrong universal client for server based
applications, but web applications work.

Pragmatism sometimes trumps correctness.

------
viraptor
> Conclusion: What DNS is not is a mapping service or a mechanism for
> delivering policy-based information. [...]

I hope noone shows him how ENUM works. Learning about a dns service that
returns a regex (NAPTR, mapping & policy-based) so that you can rewrite your
uri and query again (SRV), so that you can query again (A) could give him a
heart attack - both because it's what DNS is not (apparently) and because it
can be broken in 3 different ways by wildcards. In internal networks they're
used quite often with a very low TTL for quick routing updates.

~~~
abalashov
I was just thinking that; ENUM / e164.org is the ultimate perversion. :-)

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sirbyt
Multi-Billion dollar business vs. pointless elegance. I wonder who will win
the argument.

~~~
neilc
Another way to phrase that would be "Short-term advertising revenue vs.
ensuring the vitality of fundamental Internet infrastructure."

~~~
tptacek
CDNs threaten the vitality of fundamental Internet infrastructure _how_? CDNs
_are_ the vitality that keeps the fundamental Internet infrastructure
relevant.

W.r.t. the NXDOMAIN trickery, though, he's completely right.

~~~
neilc
Yeah, I was talking more about the NXDOMAIN stuff. As for CDNs, his gripe is
with implementing CDNs via DNS, not the CDN concept itself.

~~~
tptacek
Yeah, and implementing CDN GTM with DNS doesn't threaten the Internet (the
NXDOMAIN thing, again, clearly does).

