https://answers.launchpad.net/ubuntu/+source/dns-root-data/2023112702~ubuntu0.20.04.1
から辿って、
https://bugs.launchpad.net/ubuntu/+source/dns-root-data/+bug/2045297
から
https://b.root-servers.org/news/2023/05/16/new-addresses.html
> USC/ISI is renumbering both its IPv4 and IPv6 addresses for b.root-servers.net on 2023-11-27.
ふむふむ。