I had the opportunity at work to research DNS configuration for a cross-cloud setup between GCP and AWS. Since there were things I had forgotten or didn't know, I am recording the results of my research here.

DNS cache server
- Also called a full resolver. Waits for name resolution requests from clients and makes recursive queries to DNS authoritative servers.
DNS authoritative server
- Also called a DNS content server. Receives name resolution requests from DNS cache servers. If it holds zone information, it returns an IP address. If not, it returns the IP address of a lower-level authoritative server.
Root servers
- DNS root servers. DNS cache servers first query the root servers.
TLD (Top Level Domain)
- gTLD
  - Generic TLD
  - General domains not specific to a country, such as .com
- ccTLD
  - Country Code TLD
  - Country-specific domains such as .jp
Query forwarding
- Forward queries for specific domains to an authoritative server
Zone transfer
- Transfer zone information to an authoritative server. Used for redundant DNS server configurations.
- Previously, secondary DNS servers would Pull zone information, but now Push configurations are more common, where the primary server sends a notification (DNS NOTIFY).
BIND
- Used to build DNS servers on Linux.
rndc
- A command-line tool that allows management of the named service from both local and remote machines.
- After modifying /etc/named.conf or zone information, run rndc reload to apply the changes.

References

www.nic.ad.jp

access.redhat.com

lpi.or.jp

atmarkit.itmedia.co.jp