What is CIDR Notation?
CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP address ranges using a base IP address followed by a slash and prefix length. For example, 192.168.1.0/24 represents all 256 addresses from 192.168.1.0 to 192.168.1.255.
Prefix Length, Host Bits, and Address Ranges
A CIDR notation consists of an IP address and a suffix indicating the number of fixed bits in the network prefix. The remaining bits define the host range. A /24 network has 24 fixed bits and 8 variable bits, allowing 256 addresses. A /16 has 65,536 addresses. A /32 represents a single IP. When a website blocks a CIDR range, all IPs within that range are affected. CIDR is used in routing tables, firewall rules, access control lists, and proxy subnet documentation.
Understanding CIDR is practical for proxy work. If a target blocks 45.32.100.0/24, all 256 IPs in that range are gone. When evaluating a proxy pool from Hex Proxies accessible through gate.hexproxies.com:8080, seeing IPs spread across hundreds of different /24 ranges means a single range-level block only removes a tiny fraction of available IPs.
CIDR Awareness for Pool Evaluation
Understanding CIDR notation is essential for proxy users who manage IP allowlists, configure firewall rules, or evaluate proxy pool diversity. When a target blocks a /24 range, all 256 IPs in that subnet become unusable. Hex Proxies distributes IPs across diverse CIDR ranges to minimize the impact of range-level blocks on overall pool availability.
Why It Matters for Proxy Users
CIDR notation appears constantly in proxy work: in firewall rules, IP whitelisting, pool diversity reports, and blocking analysis. Being able to quickly calculate how many IPs a CIDR range covers and whether two IPs share a range is a practical skill that saves debugging time. A /24 covers 256 IPs, a /16 covers 65,536, and a /32 is a single IP. These numbers help you assess pool diversity and understand the scope of range-level blocks.
**Practical example:** A proxy user receives a report that their target has blocked the 198.51.100.0/24 range. They check their Hex Proxies assigned IPs and find that 4 of their 500 allocated IPs fall within this range. Because the pool spans over 200 unique /24 ranges, this single block affects less than 1 percent of their available IPs. They flag these 4 IPs for replacement and continue operations with the remaining 496 IPs unaffected, demonstrating the practical value of CIDR-diverse proxy pools.
For users managing IP whitelists on their own infrastructure, CIDR notation simplifies firewall rules. Instead of whitelisting 256 individual IP addresses, you whitelist a single /24 range. When configuring security groups, firewalls, or access control lists that govern proxy traffic, CIDR notation is the standard syntax accepted by virtually all networking equipment and cloud providers.