Why dns is required?

Answer 1

Without a Name Service there would simply not be a viable internet. To understand why we need to look at what DNS does and how and why it evolved.

1. A DNS translates (or maps) the name of a resource to its physical IP address - typically referred to as forward mapping

2. A DNS can also translate the physical IP address to the name of a resource - typically called reverse mapping.

Big deal.

Remember that the Internet (or any network for that matter) works by allocating every point (host, server, router, interface etc.) a physical IP address (which may be locally unique or globally unique).

Without DNS every host (PC) which wanted to access a resource on the network (Internet), say a simple web page e.g. www.thing.com, would need to know its physical IP address. With 100 of millions of hosts and billions of web pages it is an impossible task - it's also pretty impossible with just a handful of hosts and resources.

To solve this problem the concept of Name Servers was created in the mid 70's to enable certain attributes (properties) of a named resource to be maintained in a known location - the Name Server.

With a Name Server present in the network any host only needs to know the physical address of a Name Server and the name of the resource it wishes to access. Using this data it can find the address (or any other stored attribute or property) of the resource by interrogating (querying) the Name Server. Resources can be added, moved, changed or deleted at a single location - the Name Server. At a stroke network management was simplified and made more dynamic.

Answer 2

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. Not suprisingly people have a far easier time remembering a web address that is composed of words that relate to the subject of a web site than to the 4 octet number that is the numerical value the web address is translated into by the DNS. DNS also allows searches for web sites where the user has some idea what the name is but doesn't know it exactly. It is pretty easy to figure out that the correct web site name is "Google" when you type in "goggle", but if the right address is 172.151.62.10 and you put in 182.151.62.10 you will be nowhere near the right place. (I pulled those numbers out of thin air - I have no idea what web site they might go to - or even if those IP address have been assigned to anything).