Internet Relay Chat (IRC) is a real-time communication protocol. When a client connects to an IRC server, it must first identify itself using two mandatory commands:
NICK - Specifies the nickname the user wants to use.
USER - Provides user information such as username, hostname, and real name.
These are the very first commands required to establish presence on the IRC network.
From CEH v13 Official Courseware:
Module 7: Social Engineering
Module 19: IoT and Other Emerging Threats (includes botnets and IRC)
CEH v13 Study Guide states:
"When connecting to an IRC server, the client must first send the NICK and USER commands to register the session. Without these, the server will not establish a full connection." Incorrect Options:
B, C, D: LOGIN and PASS are not valid IRC protocol commands in this context.
Reference:RFC 2812 - Internet Relay Chat: Client Protocol (Section 3.1)CEH v13 Study Guide - Module 19:
IRC Botnet Communications