I am currently in the process of developing a VPN service. One of the necessary things for a proper VPN node is a DNS server that will prevent DNS leaks, and whilst working on this project I stumbled upon two well-known DNS servers: Bind9 and Unbound. Bind9 is an authoritative DNS server, Unbound is a caching recursive DNS server. I've looked through some differences between them, but I still can't decide which one will be better for the purpose of preventing DNS leaks. Can you help me with that decision, please?
Also at some forum I saw that Bind9 has got some reliability and security issues, is it true? How safe would it be to use Bind9 in a big public project?