CIDR Notation Explained (e.g., 203.0.113.0/24)

CIDR is a notation for IP ranges like 203.0.113.0/24. It helps describe how IP address blocks are allocated and routed.

What does /24 mean?

The /24 is a prefix length: it means the first 24 bits are the network portion. The remaining bits represent addresses inside that network.

Why CIDR shows up in IP tools

• IP ranges are allocated to ISPs and organizations in CIDR blocks
• Routing announcements (BGP) advertise prefixes
• Security teams use CIDR to block/allow ranges

Related glossary terms: CIDR, ASN, and NAT.

To see the network details for a public IP, use the IP Address Lookup.