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SSCP · Question #1154

Which range defines "well known ports?

The correct answer is B. 0-1023. Well-known ports are those ranging from 0 to 1023, assigned by IANA for common network services.

Submitted by fatima_kr· Apr 18, 2026Network and Communications Security

Question

Which range defines "well known ports?

Options

  • A0-1024
  • B0-1023
  • C1-1024
  • D1024-49151

How the community answered

(18 responses)
  • B
    89% (16)
  • C
    6% (1)
  • D
    6% (1)

Why each option

Well-known ports are those ranging from 0 to 1023, assigned by IANA for common network services.

A0-1024

This range includes 1024, which is the first registered port, not a well-known port.

B0-1023Correct

The Internet Assigned Numbers Authority (IANA) divides the 65536 available ports into three ranges: well-known ports (0-1023), registered ports (1024-49151), and dynamic/private ports (49152-65535). The well-known ports are reserved for system processes and commonly used services like HTTP (80), FTP (20, 21), and SSH (22).

C1-1024

This range excludes port 0, which is part of the well-known port range and can be used by services, though it's typically reserved.

D1024-49151

This range defines the "registered ports" or "user ports," which are distinct from well-known ports.

Concept tested: TCP/UDP port ranges

Source: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml

Topics

#Well-known ports#TCP/UDP#Networking protocols#Port numbers

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