# IPv4 Address

- 32-bit
- 2^32 4,294,967,296 possible addresses under IPv4 - now ran out.
- Can be referred to in binary, hex, octal, dotted decimal and decimal.
	- 10.10.10.10 (Dotted Decimal)
	- 00001010.00001010.00001010.00001010 (Decimal)
- Structured to aid routing
	- Network Number (globally unique, find correct network)
	- Host Number (locally unique, find correct node)
	- ^ outdated
- No. bits allocated to each part varies depending on how many host numbers needed (see: subnetting, netmask)
- Nodes with the same network number are on same network, and vice versa.
- Network number tells transmitter which case is true.

## Classful IP Addresses

![](Pasted%20image%2020240923122346.png)

- A and B have large address ranges.
- Either need multiple network numbers, or use subnets to pretend you have multiple network numbers
- One LAN per building, big network likely to be split into smaller networks. (Subnets)

255.0.0.0
/8
16.0.0.0
255.255.0.0
/16
255.255.255.0