I think it is worth noting that, while hard-coded, this line suggests that the DA list can be overridden ( https://gitweb.torproject.org/tor.git/tree/src/or/config.c#n... ). Theoretically this should allow the Tor project to provision replacement servers and publish their IP addresses without modifying the "hard-coded" list in every Tor client. With that said, I know very little about Tor and this comment should be taken with a boulder of salt.