# Internet address

# Network addresses

IP Address Format

each computer in TCP/IP network must be givent a UNIQUE identifier, or IP Address
This address, operating at Layer 3, allows 1 computer to locate another computer on a network

Format

IP = NETWORK ADDRESS + HOST ADDRESS = 32 bits . E.g: 131.108.122.204

Network layer communication path

Using the IP address of destination network, a router can deliver a packet to the correct network
To router forwards packets, the packets must include an identifier for both the source & destination networks
The network address helps the router identify a path within the network cloud
The router uses the network address to identify the destination network of a packet within an internetwork
The router uses the IP address to locate the particular computer connected to that network

Mac address vs IP address

# Types of IP address

Types of IP address

# IP Address classes

classes

Class A

possible network address from 1.0.0.0 to 126.0.0.0
Have up to 16.777.214 possible IP addresses (2²⁴ - 2)

Class B

possible network address from 128.0.0.0 to 191.255.0.0 (2¹⁴)
Have up to 65.534 possible IP addresses (2¹⁶ - 2)

Class C

possible network address from 192.0.0.0 to 223.255.255.0
Have up to 254 possible IP addresses (2⁸ - 2)

Notes

127.0.0.1 => loop back localhost
Reserved IP address
- Network address - used to identify the network itself. An IP has 0s in all host bits
- Broadcast address - used for broadcasting packets to all devices on a network. An IP has 1s in all host bits

# Public IP address

the stability of the Internet
Unique addresses are required for each device on a network. To make that an organization known as the Internet Network Information Center (InterNIC) handled this procedure. Now replate by the Intreernet Assigned Numbers Authority (IANA)
must be obtained from an Internet Service Provider (ISP) or a registry at some expense

# Private IP address

According to RFC-1918
Class A: 10.0.0.0
Class B: 172.16.0.0 - 172.31.0.0
Class C: 192.168.0.0 - 192.168.255.0

# IPv4 versus IPv6

4 octets vs 16 octets

# Subnetting

# Why?

reduce the size of a broadcast domain, optimized network perf
improve network security
simplified management
facilitated spanning of large geographical distances

# How

Format

IP = NETWORK ADDRESS + SUBNET ADDRESS + HOST ADDRESS

To create a subnet address, network admin borrows bits from original host portion & designates them as the subnet field.

# Subnet mask

A subnet mask is a 32-bit number created by setting host bits to all 0s and setting network bits to all 1s. In this way, the subnet mask separates the IP address into the network and host addresses.

cal

Example

IP	Subnet mask	CIDR	Net ID	Subnet ID	Host ID
12.10.1.2	255.0.0.0	/8	8	0	24
186.16.48.1	255.255.0.0	/16	16	0	16
192.48.96.1	255.255.255.0	/24	24	0	8
12.10.1.2	255.192.0.0 (192 = 11000000)	/10	8	2	8
186.16.48.1	255.255.224.0 (224 = 11100000)	/19	16	3	8
192.48.96.1	255.255.255.240 (240 = 111100000)	/28	24	4	8

CIDR = Classless Inter-Domain Routing or supernetting

# Tools

← Network Obtaining IP / ARP / DHCP →