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IPv4 Address Class Identifier

Enter an IPv4 address to identify its classful network class and default subnet mask.

How to use this tool

  1. 1Enter an IPv4 address.
  2. 2See its classful network class (A-E) and default subnet mask.

Frequently asked questions

Is classful addressing still used today?+

Modern networks use classless (CIDR) addressing, but classful classes are still a common reference point for understanding default masks and legacy documentation.

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