An expired 5 euro domain gave a researcher DNS control of three territories' ENUM zones, and logged about 209,000 phone-number queries before the NCSC took it over

Sources: lina.sh write-up, HN discussion
Summary: Three territories' zones under e164.arpa were delegated to a nameserver whose own domain had lapsed, so registering that expired domain for 5 euros put the author, lina, in authoritative control of every name beneath them. The post reports 100,170, 99,902 and 9,133 queries across the zones, roughly 209,000 in total, and a footnote states that a friend ran a second nameserver without logging, so the published figures are roughly half of what arrived. The national cyber security centre subsequently took the domain over. The logs are ENUM DNS lookups, and the step from those lookups to conclusions about who was placing calls is the author's inference rather than something the query data establishes.
Comments: HN commenter tosti quotes the passage drawing that conclusion and calls it a jump from the logged data. Commenter toast0 states ENUM is less dead than the post assumes, because number-porting services still issue ENUM queries against private nameservers reached over VPN.
Why it matters: A zone can be delegated to a nameserver whose own domain has lapsed, which turns the 5 euro registration of that expired nameserver domain into control of every name beneath the zone.