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#Network

An [[IP Address]] address always has a subnetwork mask (sth like 255.255.255.0)

always first 1s and then 0s. 0 can never come before 1 in a Subnetwork Address.

CIDR notation (24)

Example : 0.0.0.0 / 24 IP address / 24 (means there are 24 piece 1s and 8 pieces of 0s in the subnetwork mask, because it's 32 bits in total)

Example: 10.15.156.43 Subnet part : 10.15.156.0 Host part : 0.0.0.43

Example: 192.168.0.1 (ip address) 255.255.255.0 (subnet mask) : 1111 1111 . 1111 1111 . 1111 1111 . 0000 0000

we use AND logic to find the; subnetwork address : 192.168.0.0

if multiple devices are on the same subnetwork address, they can intercommunicate

Finding the Subnetwork Address IP address + Subnetwork Mask : gives us the Subnetwork Address

On one network we can have maximum 256 machines. Realistically 256-2: 254 because first and last are reserved to the hosts (0 and 256).

0.0.0.0 / 29 = means that 32-29 = there are 3 zeros. so we get 2^3 = 8 , which means that we have 8 machines on the network

means that 0.0.0.0 to 0.0.0.7 there are machines (like 0.0.0.1, 0.0.0.2, ...) but the first address and the last address are reserved for hosts so we exclude them, means that we have only 6 devices on the network.

[[Network Address]] ; first address in a subnetwork like 0.0.0.0 [[Broadcast Address]] ; last address in a subnetwork like 0.0.0.7 (if there are 8 addresses)

Exercise

How many devices are there on the sub-network? Can these devices intercommunicate?

PC A: 192.168.100.4 / 28

PC B: 192.168.100.17 / 28

PC C: 192.168.100.30 / 28

28 : 1111 1111 . 1111 1111 . 1111 1111 . 1111 0000 : 255.255.255. 1111 0000

We calculate according to the AND Logic.

Exercise 2

A : 127.63.10.17 / 25

B : 127.63.10.120 / 25

C : 127.63.10.130 / 25

  • How many devices are there?
  • How many IP addresses are there?
  • Can these devices intercommunicate?
  • What is the network address?
  • What is the broadcast address?

25 means : 255.255.255 . 1000 0000

there are 7 zeros, so 2^7 : 128

There are 128 IP addresses on the network. There are 126 devices/machines on the network.

A: ....17 : .... 0001 0001 subnet : .... 1000 0000

With the AND logic

127.63.10.0 is the subnet address

127.63.10.127 is the broadcast address

A and B are in the same subnetwork, they can intercommunicate

C is in the subnetwork starting with the 127.63.10.128 subnet address

Voila.