In this new series of blog posts, Jon Dainton will be breaking down the history of the internet, from inception to present day, and describing the basics, fundamentals and complexities of how the internet works.
In the first part of how the internet works we talked about how names are easier to remember than numbers. Hostnames were in use for some time, but what is a domain name?
Like a hostname, a domain name is a unique name that is easier to remember than an IP address.
The diagram below shows the structure of domain names. At the top of the tree is a ‘root’ server. This has the details of all the first level domains on the next node down. Each ‘node’ along the tree represents a database (this specific database is known as a registry) that contains information on all of the domain names within its area of responsibility, such as contact details and nameservers. The domains will be managed by a registrar who will submit the application for domains registrations to the registry and process updates to domains.
Before we start looking at the how computers can locate domain names, there are two important and often forgotten facts regarding domain names that are very useful in helping understanding how domains work.
The first is that DNS records for domain names have a ‘secret’ full stop at the end of them. You may be familiar with google.com but its complete domain should be expressed as ‘google.com.’ (with a full stop at the end). This is an often forgotten and seemingly insignificant point, but it is an important part of how domain names work.
The other thing to note is that computers read domain names right to left. So if we take the example of ‘support.fasthosts.co.uk.’ computers will break it up and read is as ‘.’, ‘.uk’, ‘.co’, ‘.fasthosts’, ‘.support’. The full stop at the end of the domain name (or at the start if you are a computer) tells the computer that the information can be found at the ‘root servers’ located at the top of the domain tree.
Provided you know where the root server at the ‘top of the tree’ is located, you can follow a path to your domain name. The registries are overseen by ICANN who coordinate domain names and IP addresses across the entire internet. ICANN accredit registry operators to provide domain registrations for gTLD domains.
An example of this is Verisign are the registry for .com, .net and .tv and Nominet are the registry for .uk domain extensions.
Fasthosts are a Nominet registrar for .uk domains. Fasthost are an accredited Nominet member meaning we are responsible for compliance including data quality. As part of data quality we have to ensure that all registrant details are correct. Fasthosts are a reseller for Tucows, Tucows are a registrar gTLD domain registrations are submitted by Fasthosts to Tucows who will then submit the registration with the relevant registry.
Finally, Fasthosts are registrant for the fasthosts.co.uk domain name and the have a sub-domain set up of support.fasthosts.co.uk. These zones of responsibility are shown on the diagram below.
This delegated responsibility enables the internet to change regularly without every user having to make a note of each change and ensures that no two domain names are identical.
What are the different types of domain name and what are they used for?
When the idea of using domain names to recognise other computers was conceived a strict hierarchy was put in place. So, anyone registering a domain name would be able to choose a domain name that described what the organisation was about. For example .edu domain names were used to describe places of education, while .com domains were places of commerce. They also assigned two letter domain name extensions to specific countries, for use by organisations that were country specific. These domain names at the top of the domain name tree are called ‘top level’ domain names, and are split into three main categories.
Generic Top Level Domains (GTLDs)
Generic Top Level Domain names are often called GTLDs or international domain names. These were used to describe the organisation, without specifying the country of origin, some examples are:
- .com – for commercial companies
- .org – for organisations
- .biz – for businesses
- .info – to provide information regarding a subject or topic
- .net – for networks and associations
Country Code Top Level Domains (ccTLDs)
As well as generic domain names, two digit domain names were assigned to individual countries, providing more versatility in the domain name structure. Some of these we may recognise, others are in less common usage, but some examples are shown below.
- .uk – United Kingdom
- .eu – European Union
- .us – United States
- .ca – Canada
- .fr – France
- .je – Jersey
- .gg – Guernsey
- .cn – China
- .gi – Gibraltar
- .fm – Federated States of Micronesia
FACT: The United Kingdom was to be assigned the (inaccurate) ccTLD of .gb (Great Britain), however the original Janet network had already selected .uk as the identifier for its pre-existing name registration scheme. .gb domains were assigned to the UK with the plan to convert the pre-existing .uk domains into .gb domains, but this never happened and is no longer feasible. .gb still exists (although not used) and at present the UK is the only country to be assigned two domain country codes.
New Top Level Domains (nTLDS)
In 2015 a new list of domain extensions was made available. This allowed businesses to choose more specific domain names for their business. Examples include:
How the domain structure has changed
These domain names, although methodically structured, are regulated by ICANN. As the internet became more popular, companies wanted domain names that customers were more likely to remember, rather than a domain name that is less memorable but fits in better with the structure of the domains.
As .com domain names were the most popular and memorable even non-commercial sites began registering domain names under it. Other people started registering domain names using trademarks, in the hope that the company owning the trademark would then offer to buy the domain name off them for inflated prices. This sort of activity is called ‘cybersquatting’, and there are now processes in place when this happens.
This also affected ways in which businesses purchased domain names. Rather than just registering the domain name that fitted properly into the structure of the domain tree, companies wishing to preserve brand integrity also started registering many domain extensions of their trademarked name. For instance, we at Fasthosts have fasthosts.co.uk, fasthosts.com, and fasthosts.uk to name a few.
Country Codes used as generic top level domains
County code top level domain names are administered by country-code managers. Some ccTLD providers follow ICANN’s process but also have their own policies and processes in place. Some of these country codes are regulated. For instance you are unable to register a .eu domain name unless you are based within the European Union.
Some country code domain names do not have this restriction in place and are available to anyone to register for any purpose. They are still under the control of the originating county. Some examples of country codes with generic usage are:
- .ws – Samoa (Originally Western Samoa), now used to denote 'web site'
- .cc – Cocos (Keeling) Islands – Used in a variety of different websites
- .be – Belgium
- .fm – Federated States of Micronesia – often used for FM radio stations.
FACT: When domain names were originally handed out the Pacific island of Tuvalu found its assigned domain name extension had some unforeseen benefits. The island, with a population of around 10,000 citizens was assigned the .tv extension. Naturally, the .tv extension was very sought after by television stations. An agreement was made with the .TV Corporation to become the exclusive registry and registrar for .tv domain names. Tuvalu, which was not connected to the internet and didn’t even have a television station, used the proceeds from this arrangement to increase the quality of life for its inhabitants.
Sponsored Generic Top Level Domain Names
As the distinction between domain name types became blurred, some industries started sponsoring their own generic top level domain names. This enabled them to keep domain name integrity and regulate who could register a domain name. Examples of sponsored domain names are:
- .aero – reserved for the aerospace industry. This was the first generic top level domain name to be reserved for a single industry.
- .mobi – websites need to be mobile friendly – sponsored by Google, Microsoft, Nokia, Samsung, Ericsson, Vodafone, T-Mobile, Telefónica Móviles, Telecom Italia Mobile, Orascom Telecom, GSM Association, Hutchison Whampoa, Syniverse Technologies, and VISA.
- .jobs – specifically for recruitment, intended for companies and organisations to advertise their positions in a standardised manner. This domain was sponsored by Employ Media LLC.
.uk domain names
Nominet are the registry for all .uk domain names and have arranged these into a structure reminiscent of the early days of domain names.
- .co.uk – Originally intended for companies within the UK, this is classed as a ‘fully open’ domain name where the usual conditions for registering domain names apply.
- .uk – .uk domain names are reserved for the registrant of the equivalent .co.uk domain name. The rights of registration are only in place for 5 years and ends in June 2019.
- .me.uk – Introduced in January 2002 and intended for personal websites. If it was not taken, I may register jon.me.uk for example, however due to the popularity of these domains I may be forced to register jon-dainton.me.uk instead.
- .org.uk – For non-commercial organisations. Like the .co.uk domain name, this is a ‘fully open’ domain name where the usual conditions for registering a domain name apply. This is useful for charities, trades unions, political parties, community groups, educational councils, professional institutions, etc.
- .ltd.uk – These domain names are restricted. To qualify the domain name must match the company name as registered with Companies house.
- .plc.uk – As with .ltd.uk but specifically for public limited companies.
Additionally, there are other second level domain names that are available to specific industries.
- .net.uk – For the sole use of UK internet service providers
- .sch.uk – Specifically designed for schools
- .gov.uk – For Government sites
- .mod.uk – for the Ministry of Defense
- .ac.uk – for academic sites and institutions
- .nhs.uk – for the National Health Service
- .nic.uk – for Nominet’s use (NIC stands for network information centre)
- .police.uk – for the police force