CIDR

tags :

Networking #

[ref](https://aws.amazon.com/what-is/cidr/#:~:text=Classless%20Inter%2DDomain%20Routing%20(CIDR,IP%20address%2C%20associated%20with%20it.)

• Classless Inter-Domain Routing (CIDR) is an IP address allocation method that improves data routing efficiency on the internet. Every machine, server, and end-user device that connects to the internet has a unique number, called an IP address, associated with it.
• Devices find and communicate with one another by using these IP addresses.
• Organizations use CIDR to allocate IP addresses flexibly and efficiently in their networks.

digitalocean 198.51.100.14: stream of octates: 00001111.00001111.00000000.1111111 each octate represented decimally: 0-255

For example: #

wikipedia

• 198.51.100.14/24 represents the

  • IPv4 address 198.51.100.14 and
  • its associated network prefix 198.51.100.0, or equivalently,
  • its subnet mask 255.255.255.0, which has 24 leading 1-bits.

• the IPv4 block 198.51.100.0/22 represents the 1024 IPv4 addresses from 198.51.100.0 to 198.51.103.255*.

• the IPv6 block 2001:db8::/48 represents the block of IPv6 addresses from 2001:db8:0:0:0:0:0:0 to 2001:db8:0:ffff:ffff:ffff:ffff:ffff.

Notation #

youtube

higher the number in place of “25” lower the number of hosts inside the subnet.