There is now an experimental download redirector for debian-cd image
downloads under http://debian-cd.debian.net.
Browse the usual directory listing under
http://debian-cd.debian.net/debian-cd/
(this should look just like the official main primary cd image server
linked to from the debian homepage).
Once you select a file, the server will try to redirect you to a
suitable mirror, that means: One that is up, has the file that you want,
and is close to you. If you click the "Details" link next to a filename,
you will see a page that tells you which mirrors are considered for you,
and why (where it thinks you are).
The redirector is based on "Mirrorbrain" and currently knows 129 active
working mirrors (of 150 total), so in most parts of the world should
always have a nearby server that it can send you to. Unfortunately,
debian mirrors aren't perfectly distributed, a large part of them are in
Europe and the US, so there are a few regions where it won't work that
perfectly.
The redirector verifies these mirrors are available every ten minutes,
so that mirrors that are down are taken out automatically sufficiently
fast. The content of the mirrors is currently checked only once a day
since it usually doesn't change. Of course, the idea is to radically
increase the scan rate when a new release is due, so that it learns fast
which servers already have the new release and can redirect users to them.
There is a lot more that can be finetuned here, e.g. mirrors that have
little available bandwidth can get a lower priority, or mirrors can be
restricted to use from their own country if they're known to have bad
connectivity to other countries. I plan to implement some of that, and
you can actually help with feedback if you have information that is
helpful in that respect (e.g. "our mirror has 1 gbit bandwidth inside
.fantasyland, but only 10 mbit international, it should be restricted to
.fantasyland only"). Should this one day become a proper, official
debian service, that information can be transferred, so it does make
sense to tune it even if it's just "experimental" right now.
I think that's all for now, I'm sure I'll remember what I forget a
second after I hit "Send"...