Comment 5 for bug 557316

Using geodns for ftp.debian.org would avoid raising the load of one server if ftp.debian.org is used as fallback. I asked DSA if using geodns for ftp.debian.org is planned and they responded with "no".

Nevertheless, I think using a fallback that is used just before "debrep" is resolved is preferable to bothering users by sending problem reports per mail. This fallback would only be used if the user doesn't configure apt-cacher-ng manually and chooses to skip automatic configuration in the debconf question or if apt-cacher-ng on ubuntu is used as cache for debian packages (or vice versa).

One idea you had was "if backend file foo is empty try foo.default in the same directory", I think this would be a very sane solution. You also suggested to put ftp.debian.org into the file backends_debian.default.

Just for clarification: ftp.debian.org is as far as I know a mirror like every other mirror and not some kind of "debian main mirror", a quick look at the ftpsync scripts seems to confirm this. Please ask ftpmaster if this is relevant for your decision and if you want to be sure. They might also have an opinion whether ftp.debian.org is the best fallback mirror of apt-cacher-ng.