Computer Networking · Intermediate level

Intermediate level · Module 1: TCP/IP and Subnetting · Lesson 3 of 3

TCP, UDP and Ports

Understand how applications use transport protocols.

In this lesson you will

  • Compare TCP and UDP
  • Identify common ports

Key concepts

TCPUDPportsthree-way handshake

The lesson

TCP provides reliable, ordered delivery with a three-way handshake and retransmission; web, email and file transfer use it.

UDP is faster and connectionless; DNS queries, voice and video calls often use it.

Ports identify applications: 53 DNS, 67/68 DHCP, 80 HTTP, 443 HTTPS, 22 SSH, 3389 RDP.

Step by step

  1. Compare TCP and UDP for five applications.
  2. Match ports to services.
  3. Use netstat to view connections.
  4. Explain one result.

Practice activity

Complete the transport and ports worksheet.

Expected result: Correct comparisons and port mappings.

Check your understanding

  1. Which protocol does a video call usually use?

    Show answer

    UDP.

  2. Which port does HTTPS use?

    Show answer

    443.

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