An IPv4 address has 32 bits written as four octets. Classful ranges: A 1–126, B 128–191, C 192–223, D (multicast) 224–239, E 240–255.
1Special addresses
Private: 10/8, 172.16/12, 192.168/16
Loopback: 127.0.0.0/8; IPv6 ::1
APIPA: 169.254.0.0/16
Limited broadcast: 255.255.255.255