Vishal Raj Dutta
Take a moment, and imagine life without a contacts list .Imagine having to remember the phone numbers of all those you call up. All 10 digits. Goosebumps of the wrong kind, right?
I mean Mom, Dad, and maybe even a significant other is doable, but in a world where laziness is the defining motto, it’d make life torturous.
The working of the Internet is somewhat in parallel lines. A lot goes on under the hood, but on a simplified level, every server that hosts a site on the Internet has something called an IP address. A mobile number, if you prefer. So, every website has a corresponding IP address, be it Google or Facebook or www.xyz.com. To access any website, you could type its hosting server’s IP address on the browser, and Voila! Website opens up!
But wait a minute, you say. We never have to type awkward strings of number to a browser’s navigation bar, you say. If we want to idle away on Facebook, we type in www.facebook.com, not some number! It’s so easy, you say. This, I say, with a tone of utter appreciation for the marvel that it is, is the miracle of the DNS. The Domain Name System.
Do you realise what DNS did for us? It obliterated any need for knowing any IP addresses, i.e. ‘mobile numbers’ of sites, and provided a means, rather to call a site by its name. Given the hundreds of websites we refer to every week, some every day, it’s an awful lot of burden lifted, which is what makes it path-breaking.
So, now that you know how important DNS is and how it provides such miraculous ease of use, let me tell you the story of a DNS lookup. A lookup simply refers to what happens between you typing in a site’s name and the site actually sitting pretty on your browser, while you idly stroke your touch pad.
Also, a point to be noted here: The things mentioned here are oversimplifications, obviously. But still, the motive behind this article was to show that DNS indeed is cool.
So, let’s say you type in www.yahoo.com into your browser’s navigation bar. Remember, computers identify each other on the net via IP addresses, like humans do via names. At any stage of the lookup, we are hunting for an IP address, which corresponds to the domain name we’ve typed in. If it’s found, Hallelujah! If not, we delve deeper and deeper into the system.
Initially, the browser will look up its own cache (its own ‘phonebook’), to see if it finds the required IP address. If yes, party’s over early. Else, it then goes on to query for the IP address for www.yahoo.com at the next level, i.e., the Resolver server, which is generally your ISP (Internet Service Provider). If it’s a hit, mission accomplished! Otherwise, the Resolver server, still determined to find the loot, goes up another tier to ask the Root servers.
The Root servers are basically at the top of the DNS hierarchy. There are about 13 such sets of root servers around the world, and are strategically placed around the world. Currently, about 12 organisations in and around the world control and maintain these servers. Clearly, a lot of power and responsibility rests on the shoulders of these organisations. The Root server technically doesn’t know the IP address of the required site, but knows a guy who knows it better. The TLD server.
The Root server sends the Resolver to an appropriate TLD server, i.e. Top Level Domain server. Top level domain refers to suffixes such as ‘.com’,’.org’,’.in’ etc. So when the root server sends the resolver to an ‘appropriate’ TLD server, it means one with the same suffix as in the full website name. So, for example, for our query, www.yahoo.com, the root server will direct the resolver to a ‘.com’ TLD server. However, the story doesn’t end here.
The TLD server too, shakes it head when asked if the IP address has, but directs it to an Authoritative Name server(ANS). The authoritative name servers (ANS) know everything there is to know about the sites under their databases. This is the final level of the lookup, and most certainly the IP address of www.yahoo.com will be given to the Resolver. The Resolver happily acquires it, panting, and after a few nanoseconds of patting self on the back returns to the browser with the info. The browser then visits the website through the Internet, once the IP address is received.
But the TLD didn’t just hand the query to any ANS that came along. How did it find the correct ANS to pass on the query? Is it Destiny? Nope. It’s the domain registrar. Big words, but basically when the domain, say ‘yahoo.com’ or ‘meyoulalala.com’ is purchased, they’re allotted by the domain registrar which ANS the domain can use. New registrations are then notified to the TLD servers too, and they take care of stuff!
So, yes, all this happened while you were stroking your touch pad. Not to forget millions of other users too, from all around the world, using the internet at the time. Yet, it takes less than seconds for a website to sit pretty on your browser but like our nervous system, the breakdown of its speed is mind-blowing.