Azure Classroomnotes 17/Mar/2022

Classful Networking

Preview

CIDR

  • This stands for Classless Inter-Domain Routing
ip : 192.168.0.100
SM : 255.255.255.0
   : 11111111.11111111.11111111.00000000 => 192.168.0.100/24

cidr: 192.168.0.0/23
SM  : 11111111.11111111.11111110.00000000 
      255.255.254.0
hosts => 2^9-2 => 512-2 = 510

cidr: 192.168.0.0/25
SM: 11111111.11111111.11111111.10000000
    255.255.255.128
hosts => 2^7-2 = 128-2 = 126

  • I want to create a network for my organization which should have 5000 devices. Can you suggest the Subnet Mask
total number of devices ~= 5000

2^n-2 ~= 5000

2^n ~= 5000
n=13
x.x.x.x/19
11111111.11111111.11100000.00000000
255.255.224.0

  • Now lets try to create a network which can host upto 25000 devices
2^n ~= 25000
n=15
cidr => x.x.x.x/(32-15) => x.x.x.x/17
SM: 11111111.11111111.10000000.00000000
SM: 255.255.128.0

  • Convention of Public Networks and Private Networks

    • Public Networks are ip addresses which are accessible over internet
    • Private networks are for private usage & there are some reserved ip ranges for private networking.
      Preview
  • In all the clouds and in the enterprise when we configure networking its always private network. so we will be choosing the ip range from

    • 192.168.0.0/16
    • 10.0.0.0/8
    • 172.16.0.0/12
  • Now lets learn to expand the cidr notation to find the range of ip addresses possible
192.168.0.0/16 => 192.168.0.0 - 192.168.255.255 => 65000
192.168.0.0/24 => 192.168.0.0 - 192.168.0.255
=> 255

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