Video presentation: Computer Networks and the Internet.
2.4. The Domain Name System (DNS). DNS structure, function, resolving DNS queries, DNS record format, DNS protocol messages

Computer networks class.
Jim Kurose
Textbook reading: Section 2.4 Computer Networking: a Top-Down Approach (8th edition), J.F. Kurose, K.W. Ross, Pearson, 2020.
See http://gaia.cs.umass.edu/kurose_ross for more open student resources.