Azure Classroom Series – 08/Jul/2020

Networking Basics

  • IP Address: is a numeric assigned to each device connected to a computer network to identify the device.

    • Two flavors of IpAddressing
      • IPv4: 32 bit number
      • IPv6: 128 bit number
  • IPv4 addresses:

    • has the size of 32 bits which theoritically allows to connect to 2^32 addresses. We are not allowed to use all the addresses as some of them reserved
    • An IPv4 address is represented as x.x.x.x . Each x is 8 bit number so x can be any where between 0 to 2^8-1 (255). Range of ip address ( to
    • Launch cmd and execute ipconfig Preview
    • IP address uniquely identifies your device. In the above case ip address was But why do i require subnet mask and Default gateway?
  • Basic Networking Principles

    • A device in a network can communicate with other devices in the same network
  • When we look at ip address it is representation of

    • network identifier:
      • id of your network
      • All the devices with same id can communicate with each other
    • host identifier:
      • device id on your network
  • But how would i know what is network id and what is host id by looking at ipaddress?

    • It is not possible to know network id from a ip address without knowing what subnet mask.
    ip addresss:
    subnet mask:
    network id:
    host id: 106
    ip address:
    subnet mask:
    network id:
    host id: 12.14
  • The host id size will reveal size of network i.e. how many devices you can connect on the network. Size of network => 2^n – 2 (n = size of host id in bits)

    ip addresss:
    subnet mask:
    network id:
    host id: 106
    size (hostid): 8 bits : 2^8 -1-1 : 254
    ip address:
    subnet mask:
    network id:
    host id: 12.14
    size (hostid): 16 bits : 2^16-2 : 65534
  • Older approach: Use classful addressing Refer Here

    • Possible subnet masks which i can have in this approach is
      • Class A => => number of address => 2^24-2 ~= 16,777,216
      • Class B => => number of address => 2^16-2 ~= 65000
      • Class C => => number of address => 2^8-2 ~= 250
  • Scenarios:

    • If i need a network which has to connect to 200 devices. Based on classful networking i need to use class C network
    • If i need a network which has to connect to 400 devices. Use class B. But class B is of size 65000 which is way beyond 400 (so many address will be wasted)
  • A new ip addressing scheme called as CIDR (Classless inter domain routing) convention came into play

    • Now convert subnet mask into binary
    subnet mask: 11111111.11111111.11111111.00000000
    cidr notation =>
    how many zeros => 8 (size of network)
    till what position do you consecutive 1 => 24
    size of network => 2^8-2 = 254
    subnet mask: 11111111.11111111.11111110.00000000
    cidr notation =>
    how many 1s => 23
    how many 0 => 9
    size of network => 2^9-2 => 510
    • Create a classless network for 1000 devices. Refer Here from this table find smallest number that is approximately thousand
    value=> 2^10 =1024
    so our value = 10
    10 for host id 
    subnet mask: 11111111.11111111.11111100.00000000

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