Network
CIDR Subnetting (Classless Inter-Domain Routing)
A method used to divide a large computer network into smaller, manageable pieces.
Detailed Explanation
Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing introduced in 1993 to improve address space utilization and reduce the size of routing tables. In CIDR notation, an IP address is followed by a slash and the number of bits in the subnet mask prefix (e.g. `192.168.1.0/24`), determining the network address, usable host IP range, and broadcast address. You can test this using the Subnet Calculator.
Key Technical Takeaways
- Notation format: `IP/prefix-length` (e.g. `/24` gives 256 total addresses, 254 usable hosts).
- Enables efficient address space allocation without wasting IP blocks.
- Calculates Network ID, First Usable Host, Last Usable Host, and Broadcast Address.
- Universal standard across cloud VPC configurations (AWS, GCP, Azure) and local networking.
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