What is the main function of the DNS protocol?

The primary and most fundamental function of the Domain Name System (DNS) protocol is to perform domain name resolution. This is the process of translating human-friendly domain names (e.g., www.huawei.com) into the numerical IP addresses (e.g., 182.52.131.21) that computers use to identify and locate each other on a network.

A. Remote access: This is the function of protocols such as SSH (Secure Shell) and Telnet.
B. File transfer: This is the function of protocols such as FTP (File Transfer Protocol), SFTP (SSH File Transfer Protocol), and HTTP (Hypertext Transfer Protocol).
D. Email transmission: This is primarily handled by SMTP (Simple Mail Transfer Protocol).

1. Huawei HCIA-Datacom V1.0 Training Material, Chapter 3: Network Layer Protocols and IP Addressing, Section: "DNS". This material explicitly defines DNS as the protocol used to translate domain names into IP addresses.

2. Mockapetris, P. (1987). RFC 1035: Domain Names - Implementation and Specification. Internet Engineering Task Force (IETF). Section 1, "INTRODUCTION," states that the DNS is a "hierarchical distributed database" whose data is used for "mapping domain names to various types of data, such as network addresses."

3. Stallings, W. (2014). Data and Computer Communications (10th ed.). Pearson. Chapter 27, "Internet Applications," describes DNS as a directory service that maps host names to IP addresses.