Friday 9 September 2016

Domain Name System(DNS)

  • DNS is an internet service that translates domains names into IP address.
  • The domain names are in alphabetic, because they are easier to remember than remembering IP address.
  • DNS is translates domain name into it's corresponding IP address.
  • For example, www.google.com translate to 173.194.36.51
Why DNS is important?
  • DNS is like a phone book for the internet. If you know a person's name but don't know their telephone number, you can simply look it up in a book .DNS provides this same service to the internet.
How DNS works?



  • If we do not have DNS, then we have to remember all IP addresses. It is impossible.

Primary DNS vs Secondary DNS:

Primary DNSSecondary DNS
It is referred as Master Server.It is referred as Slave Server.
It is responsible for reading data related to the domain zone and also responsible for communication with secondary server.It is responsible for obtaining zone data from the primary DNS server immediately after being set up.
It is the read/write copy of the DNS database.It is the read only copy of the DNS database.
We can add new records and make updates in Primary DNS.We can not add a records it takes directly from Primary DNS.
It has only one zone capacity.It has 255 zones capacity.
It works as a main server for all tasks.It works as a backup server when primary server fails.
Primary DNS responds for all domains.DNS server offers security through redundancy.
More Examples on DNS working:



Example for Primary DNS vs Secondary DNS:



See below video for more details: