- https://serverfault.com/questions/12854/cidr-for-dummies
- 8 bit (octet) boundaries
- 2 ^ 8 = 256 IPs per octet
- 4 octets * 8 bits = 32 bit integer (IPv4 address)
- calculate the # of IPs for /27:
- 32 - 27 = 5
- 2 ^ 5 = 224
- 256 - 224 = 32 IPs available
- /32 means 1 IP available
CIDR Dotted Quad
/24 255.255.255.0
/25 255.255.255.128
/26 255.255.255.192
/27 255.255.255.224
/28 255.255.255.240
/29 255.255.255.248
/30 255.255.255.252
/31 255.255.255.254
/32 255.255.255.255