Networking · 04 · 4 min read
IP addresses
The postal address of a device on a network, so packets know where to go.
IPv4
32 bits written as four numbers from 0 to 255, e.g. 192.168.1.10. That gives about 4.3 billion addresses — not enough for today’s world, which is why we need NAT and IPv6.
IPv6
128 bits written in hexadecimal, e.g. 2001:db8::1. There are about 3.4 × 10³⁸ addresses — enough to give every grain of sand on Earth its own address, many times over.
Private and special ranges
| Range | Used for |
|---|---|
| 10.0.0.0/8 | Private (big companies) |
| 172.16.0.0/12 | Private |
| 192.168.0.0/16 | Private (most homes) |
| 127.0.0.1 | Loopback — “this computer” |
| 169.254.x.x | APIPA — no DHCP answer |