CIDR / Subnet

CIDR (Classless Inter-Domain Routing) notation represents a range of IP addresses. The format is an IP address followed by a slash and a number (e.g., "192.168.1.0/24"), where the number indicates how many bits of the IP are used for the network prefix.

Common examples:
- /24 = 256 IPs (a typical small block)
- /16 = 65,536 IPs
- /32 = a single IP address

For proxies, subnet diversity matters: if all your IPs come from the same /24 subnet, anti-bot systems will easily identify and block them together.

How it works

The /N number indicates how many leading bits of the IP define the network. /24 fixes the first three octets and leaves the last one free, which means 256 IPs in the block. /16 fixes the first two octets, leaving 65,536 IPs. The smaller the number, the bigger the block: /8 covers 16.7 million IPs, /32 is a single IP. CIDR replaced the old class A/B/C system in 1993 and has been the routing standard since.

For anti-bot work, subnet diversity is a top-level signal. Vendors aggregate flagged IPs up to /24 and /20 ranges, so one bad neighbour in a /24 can taint every IP in the same block within hours. A good proxy pool spreads IPs across hundreds of /24s rather than packing thousands into a single /16; this is one of the structural reasons residential pools outperform datacenter pools on protected sites.