Which of the following port numbers the DNS protocol uses?

(A) 50
(B) 51
(C) 52
(D) 53

53 is the correct answer.

The Domain Name System (DNS) – Port 53. DNS is the phonebook of the Internet. Humans access information online through domain names, like company.com or cisco.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources. The process of DNS resolution involves converting a hostname (such as www.company.com) into a computer-friendly IP address (such as 155.138.45.1).