What is Subnetting?
Subnetting divides a network into smaller sub-networks, improving performance, security, and management. Subnet masks determine which portion of an IP address represents the network versus hosts.
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Calculator
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Subnet Guide
CIDR Notation
CIDR uses a slash and number (e.g., /24) to indicate how many bits are used for the network portion. /24 means the first 24 bits are the network, leaving 8 bits for hosts (254 usable).
Private IP Ranges
Common private ranges: 10.0.0.0/8, 172.16.0.0/12 (172.16–31.x.x), and 192.168.0.0/16. These are reserved for internal networks and not routable on the public internet.
Common Subnet Sizes
/24 (254 hosts), /22 (1,022 hosts), /20 (4,094 hosts), /30 (2 hosts — point-to-point links). Choose based on your needs with room for growth.