likely your DNS server is using PowerDNS. Versions before 4.1.0-rc1 had a bug with the query cache: https://github.com/PowerDNS/pdns/issues/6806 https://github

likely your DNS server is using PowerDNS. Versions before 4.1.0-rc1 had a bug with the query cache: https://github.com/PowerDNS/pdns/issues/6806 https://github.com/PowerDNS/pdns/issues/6806 This issue isn't affected by the configuration change on flag day and judging by the slow adoption so far, by the time where edns support really gets mandatory, the current version of the distro at that time will long have updated their built-in PowerDNS version.