Subnetting & Routing

Subnetting & CIDR Notation Explained

Learn how to split network ranges, calculate subnet masks, and master Classless Inter-Domain Routing (CIDR).

Key Technical Takeaways

  • •/24 Subnet: 255.255.255.0 mask -> 256 total IP addresses (254 usable hosts)
  • •/28 Subnet: 255.255.255.240 mask -> 16 total IP addresses (14 usable hosts)
  • •/30 Subnet: 255.255.255.252 mask -> 4 total IP addresses (2 usable point-to-point router hosts)
  • •/32 Subnet: 255.255.255.255 mask -> Single individual host route

Subnetting is the practice of dividing a single physical or logical IP network into smaller, contiguous sub-networks (subnets). CIDR (Classless Inter-Domain Routing) replaced legacy classful networking by appending a slash and prefix length (e.g., /24) representing the number of fixed network bits.

Interactive IP & Network Tools

Subnet Calculator →CIDR Calculator →IP Range Calculator →