1. DNS/PowerDNS

https://www.powerdns.com/

Our Authoritative Server, Recursor and dnsdist products are 100% open source and 100% supported, with Service Level Agreement backed 24/7 contracts available. 

Both the PowerDNS Authoritative and the PowerDNS Recursive Servers are
available in source form, as well as installable Linux Packages.

https://www.powerdns.com/downloads.html

DNS/キャッシュサーバ/PowerDNS

/Recursor

https://doc.powerdns.com/md/