Re: Small DNS questions.

[Martin Langhoff]

On Mon, Jan 26, 2009 at 8:06 AM, Michael Stone  wrote:
>  http://wiki.laptop.org/go/Network_principles#Name_resolution

Even if we were to do all sorts of DNS smartypants stuff - the only
protocol where we can play games is http. The protocol is highly
proxy-able, redirect-able and nimble, and most importantly, all the
_clients_ are specially adept and handling odd "bait-and-switch"
abuse.

For example, the kind of behaviour that you see when connecting to
commercial Wifi hotspots -- these days they mostly do the right thing
(unless your initial connection was https), but they used to muck with
DNS. Badly.

Every other (useful) protocol I can see in my /etc/services breaks if
you try this stuff. Maybe some limited interactions work -- like with
SMTP -- but overall, it just doesn't work.

We can muck with HTTP with a transparent proxy that allows us to serve
some "remote" URLs locally. I want to avoid it, but if we have to do
it, we will. Every other protocol - I plan to leave alone :-)

cheers,



m
-- 
 martin.langh...@gmail.com
 mar...@laptop.org -- School Server Architect
 - ask interesting questions
 - don't get distracted with shiny stuff  - working code first
 - http://wiki.laptop.org/go/User:Martinlanghoff
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Small DNS questions.

[Michael Stone]

Scott,

I've been conducting some thought experiments with the imaginary DNS server you
describe in

  http://wiki.laptop.org/go/Network_principles#Name_resolution

and I've developed a couple of small questions which I'd like your advice on,
e.g.

  a) When multiple links are present, does the DNS server synthesize an  RR
 for every link?

  b) Presumably the DNS server should report itself as non-authoritative for
 everything except the local hostname(s)?

  c) Presumably the synthesized RRs should be non-authoritative except when
 they answer the local hostname(s)? 

  d) How should the TTL of the synthesized records be set given that the
 records are link-dependent? (on a mobile device?)

  e) When, exactly, should our DNS server synthesize RRs? Some possible
 choices: 
 
   "always", 
   "when you can't get any other results",
   "when you didn't find NXDOMAIN", 
   "configurable"
   __
   
Thanks,

Michael

P.S. - People who are unfamiliar with the ideas and questions in this note who
would like to contribute to the conversation should probably spend some time
reading RFCs 1034, 1035, and 2460 and Scott's "Network Principles" document.
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