If you have a situation where the DNS server just stops working - what a mess. After some time nothing works and people asks questions. DNS is the Phone book of the interweb - without it everything grinds to a halt.
Networking
Building on the part one: Domain Name Servers are used in corporations. Enterprise networks typically have many subnets in the rfc-1918 range like 10. or 172. range, divided by function, department, floor of building and/or division - there is many ways to skin a cat. #DNS
Basics
Domain Name Servers DNS are the cornerstone in networking. Usually you have several running in each network - just in case. Proxmox clusters can run a name server on each node and the hidden primary in HA. BIND 9 is an open source DNS software system including an authoritative server,
Build
Without DNS nothing works. On any corporate network you will find several DNS server, several NTP servers and a lot of Firewalls. – Shouldn't the lab also have multiples of the core services, just in case.