CompTIA A+ 1101 - 2.1 Port Purposes

TCP/20 - FTP

Transfers data

TCP/21 - FTP

Controls data transfers

TCP/22 - SSH

Encrypted communication link

TCP/23 - Telnet

Telecommunication Network, login to devices remotely, in-the-clear communication

TCP/25 - SMTP

Server to server email transfer, sends mail from a device to mail server

UDP/53 - DNS

Converts names to IP addresses

UDP/67 - DHCP

Automated configuration of IP address, subnet mask and other options (server-side)

TCP/80 - HTTP

Web server communication

TCP/443 - HTTPS

Web server communication with encryption

TCP/110 - POP3

Receive emails from an email server, basic mail transfer functionality

TCP/143 - IMAP

Receive emails from an email server, includes management of email inbox from multiple clients

UDP/137 - NetBIOS

name resignation and resolution for NetBIOS over TCP/IP

TCP/139 - NetBT

session-based communication for file and printer sharing over NetBIOS

TCP/445 - SMB/CIFS

direct SMB communication over TCP without NetBIOS transport

UDP/161 - SNMP

sends requests to network devices to retrieve management information

UDP/162 - SNMP

asynchronous notifications sent from network devices to a management system, indicating a specific event or condition

TCP/389 - LDAP

store and retrieve information in a network directory

TCP/3389 - RDP

shares a desktop from a remote location

UDP/68 - DHCP

Automated configuration of IP address, subnet mask and other options (client-side)