Prop 312: 3.2.3 Limit Directory Authority Addresses to Address and ORPort
For security reasons, directory authorities only use addresses that are explicitly configured in their torrc. Since local interface addresses are implicit, and may depend on DHCP, directory authorities do not use this address resolution method (or any of the other, lower-priority address resolution methods).
See proposal 312, section 3.2.3, directory authority case: https://gitweb.torproject.org/torspec.git/tree/proposals/312-relay-auto-ipv6-addr.txt#n388