IPV4
IPV4 is a protocol for assigning unique addresses to devices on a network. An IPV4 address is a 32-bit number, typically written in dotted decimal format like 192.168.0.0.1.
Note: each dot divides (0-255) segments.
CIDR
CIDR is a method for specifying IP address ranges and subnetting. It uses slash notation (e.g. /24 to indicate how many bits are used for the network part of the address)
For example in the IP address 192.168.1.0/24. The /24 means first 24 buts are for the network, and 8 bits are for host addresses. This covers 192.168.1.0 to 192.168.1.255 (256 addresses).
Subnet Mask
Subnet mask is another way of expressing the same thing: how the IP space is split between network and host.
| CIDR | Subnet Mask | # of IPs |
|---|---|---|
| /8 | 255.0.0.0 | 16.7M |
| /16 | 255.255.0.0 | 65,536 |
| /24 | 255.255.255.0 | 256 |
| /32 | 255.255.255.255 | 1 (single IP) |