What port numbers should you know for the Security+ exam?

Key port numbers include HTTP on port 80, HTTPS on port 443, FTP on ports 20 and 21, SSH and SFTP on port 22, Telnet on port 23, SMTP on port 25, DNS on port 53, DHCP on ports 67 and 68, TFTP on port 69, POP3 on port 110, IMAP on port 143, SNMP on ports 161 and 162, LDAP on port 389, LDAPS on port 636, FTPS on port 990, RADIUS on ports 1812 and 1813, and RDP on port 3389. The exam expects you to identify insecure protocols and their secure alternatives. For example, replace Telnet port 23 with SSH port 22, and HTTP port 80 with HTTPS port 443.