Subnetting divides a large network into smaller networks. Example: 192.168.1.0/24 < 256 devices Can be split into:

  • 192.168.1.0/26
  • 192.168.1.64/26
  • etc.

Why it matters in security ?

without subnetting:

  • Everyone can access everyone
  • Malware spread easily

with subnetting:

  • HR network separated from IT
  • Servers separated from users
  • Attack spread limited

This prevent lateral movement.

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