Why do we need DNS Root Servers?
Look at the list of top level domains in Snyder on page 67. Can you find your initials? What country do you stand for? Where is the top level domain in the URL hierarchy?
So, now that you know that data is shipped all over the Internet, even between countries, you may be wondering how information gets back to you without getting lost. The truth is, it doesn't.
Information is getting lost all the time. Fortunately, many protocols have been developed to limit the damage caused by dropped packets. There are protocols for times when data is more important than speed (TCP) and protocols for when speed is more important than data (UDP).
The average webpage request is processed over TCP. This means that a message is broken up into tiny pieces and shipped off in different directions. Often, most of the pieces take different routes to their destinations, so we have to label them very well to make sure they all get to their final destination. If the sender doesn't receive confirmation that a given packet has made the journey, it will send a replacement.
This is all very handy, but how do we know where the data is going in the first place? Well, we read the URL, of course. The URL delivers us right to the exact location of the final HTML file. In order to create a URL, we need to understand the file structure of the internet. This hierarchy is important for proper network organization.
Imagine a workplace with a CEO who oversees Managers, then the Managers oversee Supervisors. Finally, Supervisors oversee the workers who provide the actual content. Even more similar is the structure of our computer hard drives. What part of our computer would be the CEO? What would the Managers be? How about the Supervisors? The Workers? Now, translate that one more little bit to a web server. Now, the domain server is the CEO. It's at the top level. The name servers are next, followed by the folders and finally the working files.
This hierarchy structure is repeated frequently in computer science. You'll see it more as we start to talk about HTML, XML and even in some algorithms.
Additional Links for this Session
* HTML Hierarchy
* Tree Structure
* Grace Hopper Describes a Nanosecond
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