Daily Learning: Computer Networks – IP Address & DNS

IP Address

When we type google.com in our web browser it is converted into IP addresses and then it reach to the desired google network and host and specific port to get the web page.

An IP address consists of two part –

  1. Network ID
  2. Host ID

The size of IP address is 32 bit.

Generation

  • 1st Gen – In 1980 the IP address was divided into 8 bit or Network ID and 24 bit of Host ID but as people starts using computer more the requirement got more.
  • Classful System – We have divided the IP address into various classes –

Class A we take the first bit, Class B we take the first 2 bit, similarly in Class C we take the first 3 bit and so on till Class E.

ClassStarts WithNetwork BitHost BitTotal NetworksHost per NetworkNetwork Range
Class A01 + 72412816M1-126
Class B102 + 141616K65K128-191
Class C1103 + 21820M256192-223
Class D1110Reserved For MulticastN/AN/AN/A224-239
Class E11111Reserved For ExperimentN/AN/AN/A240-255

What is dotted decimal representation?

If we divide the IP address in four parts(8 bits) and we convert the 8 bit into decimal and we put “.” in between it is called dotted decimal representation. e.g. – 127.0.0.1

Note : We can configure total (number of host – 2) per network.

  • suppose we have a network 11.0.0.0, 14.0.0.0. Whenever there is all 0 in the host ID it represents the network itself. That’s why we don’t use first IP address as a valid IP address for a host.
  • 255.255.255.255 is assigned as Limited Broadcast Address. So it can’t be assigned to any host.
  • 255 as host ID is assigned as Direct Broadcasting Address. So it can’t be assigned to any host. e.g – (NID).255.255.255

DNS

What is DNS overhead?

For converting the domain name into IP address we go to DNS(Domain Name Service) Server of the ISP(Internet Service Provider) and if it doesn’t know the IP then there are three hierarchy servers that helps –

  1. Root Server
  2. TLD Server(Top Level Domain)
  3. Name Server

Actually we don’t do it every time we visit a website after conversion we store the IP address locally in our computer.

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