source : https://www.isc.org/downloads/bind/
since 4.3.5, Qnap firmware is using dnsmasq bridged to resolv.conf and using port 53 by default, you need to tweak configuration to make bind works properly
Backup your config before update
config files within /opt/Bind/etc (stop application within appcenter before config modification)
BIND is open source software that implements the Domain Name System (DNS) protocols for the Internet. It is a reference implementation of those protocols, but it is also production-grade software, suitable for use in high-volume and high-reliability applications. The name BIND stands for “Berkeley Internet Name Domain”, because the software originated in the early 1980s at the University of California at Berkeley.
BIND is by far the most widely used DNS software on the Internet, providing a robust and stable platform on top of which organizations can build distributed computing systems with the knowledge that those systems are fully compliant with published DNS standards.