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Jul 282013
 

Having recently assisted with getting my sister’s business web site online (the domain and DNS side of things), it occurred to me that many people assume that it is all the same thing. Which is most definitely not the case, and believing so leaves you open to being ripped off. It is not unknown for hosting companies to “make it easy” for you to perform the whole job of registering a domain, making the relevant DNS changes, and setting up your web site. Often by hiding as much of the detail as possible.

That would be fine if that were all they did, but it isn’t. Sometimes they go out of their way to imply that if you want to change hosting companies, then you have to get a new domain, and it can take quite a bit of digging to find out how to transfer the domain elsewhere. Now it is easy to think that this doesn’t matter too much, but the longer you use a domain, the more you want to stick with it. Especially if you have a blog site that is not entirely unpopular … an older domain with lots of content has value. And the more successful you are, the more likely you are to want to change hosting companies.

Other hosting companies may offer better value on web sites with lots of visitors, or perhaps you are blogging in a controversial and need some sort of added protection against hackers, or you just “grow out” of a simple web site editing tool and want to get down and dirty with the HTML.

So it may well be worth your time finding out a little bit about this stuff in advance, and registering a domain separately to the web hosting. Or get a friendly geek to do so.

The Web Site

At their very simplest, web servers are nothing more than simple file servers. A web browser asks for an object (“give me http://zonky.org/index.html”), and the web server responds with the object (“It’s an HTML object, and here it is.”). Even on the most sophisticated web sites, the overwhelming majority of objects that make up the web page that you see, are simple files. And when you graduate to advanced features such as server-side languages (PHP, Java, etc.), the conversation between the web browser is still relatively simple one consisting mostly of simple requests for objects.

The key part of asking a web server for an object is that you need some sort of identifier for that object. This is known as the URL … Uniform Resource Locator, which could be called a “web address” (although URL is also used for non-web things). The key part (as far as we’re concerned here) is the host part of the URL. This performs two functions :-

  1. If it is not already a network address (IP address), then the web browser uses the DNS to get a network address. This is used to determine what web server to talk to.
  2. It is also included in the request to the web server. This allows the web server to distinguish between different “virtual servers”.

When it is not a network address, the host part of the URL is also known as the domain. Which brings us to the next topic.

The Domain

Domains and the DNS are very tightly associated, but in theory you could register a domain without having a DNS service. In practice it is rarely done … and almost always when you are running your own DNS service, in which case you will probably not be reading this!

But domains are distinct from the DNS service. The process of registering a domain consists of picking a name, and a top-level domain in which to add that name. It is most common to use .com for an international business (or one that wants to become one), a local business domain (such as .co.uk) for a more local business, .org for a generic organisation, etc. You can be creative with your choice of top-level domain, where the top-level domain becomes part of the entire name – such as http://bit.ly/, but that makes the registration process trickier.

Some top-level domains restrict who can register domains – the .ac.uk domain for example is really just for Academic organisations, and JANET is quite restrictive about who can register a domain with them.

When you register a domain, some of the information that you provide (such as name, address, phone number, etc.) is made public by default! Whilst you can often hide this, you may want to consider whether that is wise … domains with hidden registration information are often used by those for nefarious purposes. That is a domain with public information has a higher reputation than those without.

The Domain Name System (DNS)

The DNS is a service that allows you lookup names. It is usually used to turn named (such as zonky.org) into network addresses (81.2.106.111 or 2001:8b0:ca2c:dead::d00d), but there are also other kinds of records. A hosting provider often hides all this extra detail from you, but not always. It’s easy to overlook that with one domain, it is perfectly possible to have as many names as you have the imagination for – for example, my own domain (zonky.org) has a web site that is very rarely visited, there is also a different web site at www.zonky.org, and a separate blog at really.zonky.org (plus a few others). This can be handy if you want different web sites for different purposes – a normal web site for a business, an additional web site for a blog (to publicise the business), a forum site for customer support, etc.

Each of which could be hosted with a different hosting company!

Most of these “other” DNS record types are not of interest if all you are interested in are web sites, but one – the CNAME – may be useful. It allows you to give an “alias” to another name – i.e. make www.zonky.org point to zonky.org. If you have a web site with multiple names – for example a web site that responds at your domain name (zonky.org), and your domain name with “www” added to the front (www.zonky.org) – then it may be better to use a CNAME for the “www” to point to your domain. This is simply so that you only have to enter the network address of your web site in one location, and only update it once.

However “aliases” can only exist as aliases … there can be no other additional records associated with that name. Your domain name (zonky.org) has at least one other DNS record associated with it, so you cannot use an alias here.

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