DNS (domain name system) is a protocol and mechanism that acts as “411” of computers.
Like the telephone system, each interface on a TCP/IP network has a unique IP address associated with it. This IP address is numerical. In fact, it is just a 32-bit pattern (32 binary digits). This is the bottom line. If you want to locate an interface in a network, you need to use the IP address.
IP addresses, however, suffer from two major problems. One, people cannot remember IP addresses very well. This is why we have lettering on the telephone keypad/dial to begin with! The second limitation of IP addresses is that we only have a mechanism to identify a physical interface, but not a logical entity.
The second point requires a little more explanation. Let us consider yahoo.com. Yahoo.com is a logical organization, it can have many network interfaces for redundancy and efficiency. It is a hassle if every user has to remember the IP addresses of all the interfaces used by yahoo.com. It is even worse when a user needs to determine which interface is faster.
To solve these two problems, we have domain names. A domain name is a symbolic name that we can use to identify “domains”. Here is an example:
Would you rather remember the domain name, or the IP addresses corresponding to the domain name?