CompTIA A+ Ports and Protocols: The 220-1201 List and How to Remember It

The exact 220-1201 list, grouped by job

The A+ Core 1 objectives print the ports. Objective 2.1, version 3.0, lists the entries below and asks you to compare TCP and UDP. This page sticks to that list. Other well-known ports exist, but they are not in 2.1. Some prep lists add secure variants such as LDAPS. Version 3.0 of the objectives, checked October 17, 2026, does not list them. If you move on to Security+, Passy's guide to Security+ ports and their secure replacements picks up there.

The transport column comes from the protocol specifications and Microsoft's Windows port reference, checked October 17, 2026. IANA registers most of these numbers for both TCP and UDP, so the registry alone does not tell you which one a service actually uses.

Port numbers are defaults. An administrator can move a service to another port. Exam questions mean the default unless they say otherwise.

TCP vs UDP, and why some services use both

TCP sets up a connection with a three-way handshake before data moves. RFC 9293 describes it as a reliable, in-order byte stream. Web pages, mail, file sharing, and remote shells use TCP because a missing or reordered piece would corrupt the result.

UDP sends independent datagrams. RFC 768 says delivery and duplicate protection are not guaranteed. That means less overhead, which suits short request-and-reply exchanges.

Three items on the list are worth a second look:

• DHCP is UDP. RFC 2131 says so directly: clients send to server port 67, and servers reply to client port 68. That fits the job. A client asking for an address does not have one yet, so it broadcasts its request on the local subnet.
• DNS uses both. RFC 1035 defines DNS on port 53 over UDP and TCP. In that original specification, messages carried over UDP are limited to 512 bytes, and longer ones are truncated and flagged. That is one reason DNS also needs TCP.
• NetBIOS splits by job. Microsoft lists the name service on 137 (UDP, and also TCP), the datagram service on UDP 138, and the session service on TCP 139. SMB on 445 is "direct hosted": it runs over TCP without the NetBIOS layer. Microsoft notes that since Windows Vista and SMB 2.0.2, SMB requires TCP port 445.

So when a question asks about UDP, think of DHCP and the NetBIOS name and datagram services first. DNS is the classic "both" answer.

Ways to remember the list that actually stick

Random flashcards fade. Grouping by relationship holds up better.

1. Learn the two secure pairs on the list. Telnet on 23 and SSH on 22 do the same job, a remote command line, but only SSH encrypts the session. The numbers are even adjacent. HTTP on 80 and HTTPS on 443 carry the same web traffic, without and with TLS.
2. Learn mail by direction. Port 25 sends. Ports 110 and 143 retrieve. RFC 1939 describes POP3 as a way for a workstation to retrieve mail the server is holding, where mail is normally downloaded and then deleted. IMAP, per RFC 9051, lets a client work with messages that stay on the server. That is why IMAP suits a user who reads mail on a phone and a laptop.
3. Learn Windows sharing as old and new. 137-139 is the older NetBIOS route. 445 is SMB directly over TCP. A mapped drive on a current Windows network points you to 445 first.
4. Separate 389 from 3389. LDAP directory lookups use 389. RDP uses 3389. One extra digit, a completely different job. This is a favorite trap.
5. Tie DHCP to its two sides. The server listens on 67, the client on 68.
6. Tie FTP to its two channels. 21 carries the control connection, including commands and login. 20 is FTP's default data port. RFC 959 runs the control connection over Telnet-style strings, so plain FTP is not encrypted.

Scenario drills: name the port from the symptom

Cover the right-hand columns, read the symptom, and name the port and the reason. These scenarios are original.

Notice the pattern: most stems describe what broke, not which number. Translate the symptom into the job, then the job into the port.

See the ports on your own PC

On a Windows machine, netstat -a -n lists active TCP connections plus the TCP and UDP ports the computer is listening on, with numbers instead of names. Add -o to see the process ID that owns each connection. Match the local port numbers you see against the table above. The Windows command-line guide explains netstat alongside the other 220-1202 commands.

Ports are one piece of the Networking domain, which is 23% of Core 1. Addressing, DHCP scopes, DNS records, and Wi-Fi bands are in the A+ networking guide. When you can name the port from a symptom without the table, practice A+ port-and-protocol scenarios with explanations in Passy →, or try the free A+ practice questions first.