Domain Name Servers

Domain Name Servers

As we saw in previous lessons, in order two or moredevices to connect, a number of protocols are used. A protocol is a set of rules that governs data transmission and allows the devices to agree on how the data will be transferred. Usually, the data being requested over the internet is connected to a web page, like this one (yes, your course is a web page on the internet even though it’s hidden behind a login).

Hosting

The Cloud is another name used for storage and software that is accessed through the internet. It isn’t, as the name suggests, a special area somewhere in the sky. In fact, most we servers are large computers running in offices that have been opened up to traffic from the internet. So saving your data to the cloud, is using someone else’s hard drive in a different location (although that someone else will also be responsible for backing up the data).

FTP (File Transfer Protocol)

FTP is the set of rules (a protocol) that allows the upload of files to a webserver using valid login details.

Web pages and the files that are used by them such as images & downloadable files need to be saved in an accessible location so that when a user connected to the internet requests access to the page, they can be sent to the user’s internet browser.

Web servers can be run on any computer with an internet connection, but because they need to alow traffic in from the internet, they are often run by technical specialists who add additional anti-virus & firewall protection to the servers.

Often people talk about buying ‘hosting’ for their website. This simply means that they are renting space on a webserver to store their website files which are then accessed using the servers IP address.

Activity

Check your understanding of our key terms so far with the game below:

Domain Name System (DNS)

Once a website has been loaded onto the webserver, the users need a way to access the website. They do this using a URL (Uniform Resource Locator) – this a human-friendly address given to the website that is made up of several sections. In your exam, you will need to recognise and descrive each of these sections.

A URL:

https://www.TeachAllAboutIt.uk/home.html

https:// – This is the protocol that is being used to access the webpage. In this case, Hypertext Transfer Protocol Secure

TeachAllAboutIt.uk – This is the Domain Name for the website. It’s the text based, user friendly way to name the site

home.html – this is the file name of the webpage you are accessing. Sometimes there are other words before the file name which show the folder (also known as the directory) structure, but often this is hidden to help protect the site.

The sites DNS is a database of all registered URLs which matches them to the IP of the webserver.

Different parts of a site may point to different servers. For example, the website may be stored in one location, email on another, and a database on another. Using the DNS, the same URL can be used for each because of the protocol used.

When you type a URL into your web browser a request is sent to your nearest Domain Name Server. This will look up the IP Address of the website in a large database that is maintained across the internet.

Once the Domain Name Server has found the IP address, it sends on the request from your browser to the correct IP address on the internet.

Because your request contains a data packet with your own IP on it, the Web Server is able to send back your data over the internet directly.

The Role of The Browser

The Role of The Browser

When we discuss networks, we should be aware that they don’t always need connection to the internet. However, the internet is an example of a WAN (Wide Area Network). Understanding how the internet works also gives us an insight into how smaller networks transmit data.

A web browser is a piece of software that allows the user to access web pages which are stored on the Internet. By typing in the URL for uniform resource locator into the address bar off the browser it can communicate with your Internet service provider to request the data from the web server where the web page is located. We were looking to ISPs in more detail in the next lesson.

Web browser software is a type of application software. This means that it allows the user to perform a task rather than control the system as is the case for utility software. Browsers have a number of features that allow us to access and interact with the various web pages on the Internet.

Most web browsers will allow you to bookmark a page. This creates saved link which can be used to quickly access that web page again either using an icon or a menu.

The ability to have multiple websites open using different tabs is a feature of most modern web browsers. This allows us to not only access multiple web pages but use them at the same time swapping between tabs which are clickable links to each window. The downside of having multiple tabs open is that this takes up CPU processing time and space within the ram as the web page is currently open. This means that the more tabs you have open the slower your system will run.  

There are a number of different web browsers available and because all web browsers must work with the same HTML code, many are very similar. Some well-known examples Firefox, Chrome comma and Internet Explorer. Other web browsers such as Tor are becoming more popular as they also include features to help protect data whilst using the Internet.

Activity

Create a table to compare the different browsers available for your computer. What similar features do they have? Do they have any features that do not appear in other browsers?

Revision Task

Download the scribbl.it notes below and add your own notes to these. Which web browser do you use? How do you know that a webpage is safe? (does your browser help?)

Scribblit – The Role of The Web BrowserDownload