Every computer/server/router/mobile on a network has unique Physical Address - MAC Address.
MAC : Media Access Control is a 6 byte hexadecimal. e.g. a1:00:ff:12:bc:de which can’t be changed because its permanently embedded on network card.
On windows type : ipconfig /all and on macOS/linux machines just type : ifconfig.
Note : you can’t change MAC address, all the different tools available just hide/mask your original MAC address. MAC address is accessible only on local network.
MAC address can’t do routing and it works only on its own network.
Logical Address : IP address is more suitable and useful for routing. There are 2 naming schemes : ipv4 and ipv6. As a result its logical address, its temporary and it may change when you log out from network. This is automatically assigned by DHCP server.
ipv4 : 32 bit address, while ipv6 : 128 bit address.
Every IP address comes with a subnet mask i.e. 255.255.255.0
localhost address/loopback address : 127.0.0.1
Class of IP address : say 192.168.1.100
0-127 - A class address - N.H.H.H
128-191 - B class address - N.N.H.H
192-223 - C class address - N.N.N.H
network address is - 192.168.1.0 (first address)
host address is - 192.168.1.100
broadcast - 192.168.1.255 (last address)
Effectively you have network-2 addresses
Another example - B Class network 150.1.1.100
Concept of Private IP Address All the IPs are hidden by router so public IP address is of the router.
demo exam
layers - 7
VLSM - Variable length subnet mask
use descending order
202.1.1.0/24