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Network Ports Overview

Sep 9, 2025

Overview

This lecture explains network ports, their role in directing traffic to correct applications, how they are represented, and their numerical range in computer networking.

The Role of Network Ports

  • Network ports allow multiple services to run on a single system by directing network traffic to specific applications.
  • An IP address identifies a device, while a port number specifies the intended application or service on that device.
  • The analogy: a computer is like an apartment building (IP), and ports are the apartment numbers for applications.

Technical Structure of Ports

  • Network ports are represented as 16-bit binary numbers.
  • In decimal, port numbers range from 0 to 65,535 (2^16 possible values).
  • Port numbers start at 0, not 1, due to binary counting conventions.

Key Terms & Definitions

  • Network port — A logical access point on a computer for directing incoming/outgoing traffic to a specific application or service.
  • IP address — A unique identifier for a device on a network.
  • 16-bit number — A binary number with 16 digits, allowing for 65,536 unique values (0–65,535).

Action Items / Next Steps

  • Review the structure and function of ports and IP addresses in networking.
  • Ensure understanding of the analogy between apartment numbers and network ports.
  • Prepare to identify common port numbers and their associated services in future lessons.