Category: Extras

In this lesson we will look at understanding the DNS “Domain Name System” and how web addresses work on the internet.

Have you ever wondered how your computer knows how to find the correct web server when you type in a web address?
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When you type in a website, e.g. www.example.org your computer has to perform a lookup to translate that address into something it understands.

The computer looks up “www.example.org” in a big list, and translates the address into an IP Address.

An IP Address is a list of numbers which tells the computer how to find the correct web server for the web site you asked for. An IP address is usually in the form of four numbers separated by dots, for example 127.0.0.1. The maximum for each number is 255, so IP address range from 0.0.0.0 to 255.255.255.255.

(Note: There is a new form of IP addresses known as IPv6 which is six numbers separated by “:” characters. You can think of them as being basically the same idea but longer numbers! So don’t be confused if you see an IP address that doesn’t look like 0.0.0.0 – it’s just an IPv6 address.)

This ‘big list’ where the computer looks up the IP address is called the Domain Name System, which is often shortened to DNS.

When you register a domain name, for example, free-online-training-courses.com/ you have ownership of that address. You can point it at any IP address you like.

The domain name is just a name – it doesn't come with a web host… for that you have to get a web host! See our earlier lessons on web hosting to understand how to do this.

There are a number of companies which provide access to registering new domain names. When you buy a domain name you can log into the portal the company provides and edit the DNS records for your domain name.

So, perhaps when you register the domain name you have already purchased a web host. And you know that your web host has assigned you the IP address 127.0.0.1.
So you can log into your DNS service and change the IP address associated with your domain name to 127.0.0.1.

This causes the DNS changes to 'propagate'. This means that the big list of DNS addresses is updated all around the world. Sometimes this takes a few hours.

Then, whenever you type into a browser your domain name, e.g. www.example.org the computer will look up your domain name, find the IP address (127.0.0.1) and then it will ask your web host for your website.

At this point the web server software on your host will respond. And you already understand something about how this works from our earlier lessons!

Now you are beginning to get an idea of the entire workings of the internet and web browsers in more detail. This knowledge will help you greatly as you learn to create websites.

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In this lesson we will look at the considerations that go into choosing the correct web host for our needs.

Now you understand what web hosting is, you may be wondering how to choose a web host.
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If you search for web hosting you will see there are hundreds or thousands of companies who are offering web hosting services. How do we decide which is best?

There are a number of important considerations.

Do we want their specific platform, or do we want a generic web host?

What technology do we require from our web host?

Some web hosts offer a complete package including specialised software to create websites using their platform. For example they might have created a particular blogging engine, and if we get hosting from them it must use their blogging engine. This can be very useful as it saves us the effort of creating our own blog!

However, these platforms may not be very flexible. Perhaps they can only be used in a certain way, or for a certain kind of website. Later we may be frustrated that we cannot do exactly what we want using this platform.

The alternative approach to this is a more generic web host. For example, a web host that offers simply basic Windows machines running IIS (or Apache on Linux) gives us the complete technical freedom to do whatever we want. We can put up our own HTML files for simple websites, or we can write complex websites in a server-side language such as ASP.NET or PHP or Ruby.

The downside of this generic approach is that we have to write our own software, which is difficult and time-consuming.

Of course if you want to write a website in ASP.NET then you must choose a host which provides a web server that runs ASP.NET. And the same goes for PHP or Ruby or other server-side languages.

Sometimes there is a tradeoff – perhaps we can use a web host which provides their platform, but they allow us to customise the code for our own needs, or to run other sites alongside it for additional functionality.

Technology is the most important initial consideration, as you need to ensure your web host is capable of doing everything your website requires.

Support & Reputation

Does the hosting company you are looking at have strong support systems? Do they respond to support tickets rapidly? Hopefully you will not need much support, but it is inevitable that you will encounter problems and it is useful to have support.

It is worth noting that the hosting company is not responsible for everything to do with your site. They are responsible for ensuring the physical machine your site runs on is available and accessible, and for any software on it that they agree to install (for example the web server software). However if your site has bugs or problems they are usually not your line of support!

Sometimes it is difficult to tell whether a problem is to do with your site or to do with the web host not working correctly – in this instance you want to know that your web host is responsive to support requests so you can find out and get to fixing it!

Also always check the reputation of a company you are getting your hosting from. Hosting contracts can be cancelled at any time, but you should still ensure the business you are dealing with has a good reputation amongst its customers.

Space and Bandwidth

How much storage space and bandwidth do you get with your web host?

If you are making a small site that you will access only every now and then (for example, creating a family album just for yourself… and you don’t want to use a large photo-sharing service because you like the challenge of making your own website!) then you do not need a lot of bandwidth.

However if you intend to create a website to rival Facebook then you will need thousands of web servers and a lot of bandwidth. Of course you wouldn’t begin by getting all that bandwidth in advance! And if you are getting millions of hits per day then you should probably start developing your own computing infrastructure..!

It is important to be realistic and realise you will not have massive bandwidth needs immediately.

But it is important to estimate your traffic accurately. Will you get 1 hit per day? Or 1000? Or 100,000? In each case you need to choose the right amount of bandwidth.

Which brings us to…

Price

The more computing power and bandwidth we want the more our hosting will cost. For most sites we don’t expect a lot of traffic so we can afford to choose a lower amount of bandwidth or computing power. These days it is easy to scale up the power of a server if it starts getting more traffic than expected, so it is wise to begin with the minimum amount of power you think you will need.

You must budget wisely – can you afford the monthly cost of this host? Paying more than you need for hosting is not a good use of the money for your business or family – look carefully at the costs, compare to other hosting companies that have the same technology and choose one that appears reputable (check the reviews!), and affordable for you.

Conclusion

There are a number of important considerations when choosing a web hosting company. On the technical side you must consider the platform and software they offer, and how customisable it is. It is important to estimate your bandwidth requirements realistically. And choose a package you can afford from a reputable company.

Good luck with your hosting!

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In this lesson we will learn what is meant by the term ‘web hosting’, and we will understand more deeply how web servers create the responses to the requests from our browser.

Web Hosting is the name commonly given to the service which makes our websites available over the internet.

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Websites are uploaded to a computer known as a ‘web host’ and from there the web site is accessed. If you recall our lesson on What Is The Internet  you will realise that a web host is just another name for a server.

There is nothing particularly special about ‘web hosting’ computers – they are just computers like any other! They usually have more specialised hardware than home computers (for example more memory, or a faster harddisk) but they are essentially “just computers”.

Unlike our home computers web hosts are connected to the internet all the time. Of course this is because the website must be accessible at all times so people from all over the world can access it.

Web Host Software

Servers used as a web host are commonly configured with different software to the home computers we are used to.

There are two main ‘flavours’ of web host software: Windows and Linux.

Web hosts running Windows usually use a business/server version of Windows. This is similar to the home versions of Windows we are used to, but has some extra features for server administrators to use.

Linux is a very popular free operating system which is very common in the world of servers and web hosting.

However, the operating system is not sufficient software to run a modern website. On top of the operating system the web hosting machine also has a ‘web server’ installed.

This is confusing terminology, as the term “web server” is used to refer to the physical machine, and also this particular bit of software that runs on the machine! However, it is usually obvious from context when we are referring to a physical machine and when we are referring to the web server software.

On Windows the most common web server software is known as IIS. This is the web server provided by Microsoft.

On Linux the most common web server is known as Apache.

Both Apache and IIS are capable of more or less the same tasks, though the way in which we administer each is different. Naturally there are multiple different versions of both Apache and IIS so there is a lot of detail to be learned when mastering either of these pieces of software.

Do you remember what a web request is? If not you should review our lesson on How Web Browsers Work.

When a web request arrives at the web host the web server software intercepts it. At this point IIS or Apache (or some other web server software) decides how to respond to the request and creates the response.

Depending on the nature of the web site the way in which this response is created can be very different.

For example, if a request comes in:

1. Asking for an image. The web server simply responds with the image file.
2. Asking for an HTML page. The web server simply responds with the contents of the HTML file.
3. Asking for a page written in ASP.NET or PHP or some other server-side language. The web server calls yet another program (ASP.NET or PHP etc) and that program creates the response. This response is then returned by the web server.

There are many possible ways the web server may create a response, but these few examples hopefully give you the idea. Sometimes it is as clear as sending back an individual file. Sometimes the web server asks another program for what to send back.

This is known as a pipeline. More and more programs can be connected together in this pipeline to allow very complex responses to be created.

Now you understand in a little more detail how responses are created by web servers. If you have been following our course then you can imagine how you might put your HTML files on a web server and access them. Or maybe you can begin learning more complex languages such as PHP or ASP.NET and start generating HTML files dynamically on the server! We will work towards more understanding in future lessons.

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