What you need to know about domain names

Your address on the Internet

The Internet is like an extremely long High Street with every enterprise and member of the public living on it. Each enterprise and member of the public is assigned a number on that High Street - it’s their address.

This numerical address is known as an IP (Internet Protocol) address. You need to know about IP addresses because they will appear in documentation relating to your Internet connectivity, ie the method by which you connect to the Internet whether via BT or a third party Internet Service Provider (ISP). IP is part of the fundamental communications protocol of the Internet.

An IP address takes the form xxx.xxx.xxx.xxx for example 195.10.235.16. Your IP address is assigned by your ISP. The ISP has acquired a range of IP addresses from a higher authority up the Internet management chain. If you change ISP then you will receive a different IP address from the new provider.
The domain name system

Even with (say) a billion addresses, having to give out your Internet address as 233.192.9.23 would be fraught with difficulty. Not only is it difficult to tap in correctly, should you change ISP the number will change. To get around this the domain name system was invented to give a ‘friendly’ name to your current IP address.

In principle, what happens is that a numerical IP address on the Internet is assigned a friendly name eg mycompany. This friendly name is known as the domain name.

However, we immediately run into a problem: how do we stop two or more people having the same name? This is solved by organisations called domain registrars which exist for each country in the world.
Domain registrars

In order to manage your own domains, it’s enough to know that there are a number of international and national organisations that deal with it. In Europe, domains are managed by national organisations. In Britain, a company called Nominet has been assigned the task of UK domain management by the Government.

You probably spotted earlier that the example domain name mycompany was incomplete because it didn’t have the familiar .com or .co.uk ending. Apart from the USA, all national organisations manage just their particular top level domains (TLDs) on the Internet eg uk, fr, de, it, es for Britain, France, Germany, Italy and Spain respectively.
UK domain name registration

In the case of the UK, the top level domain space (uk) is divided into secondary levels to indicate the kind of organisation that is being represented by the domain name.

The second level domains (SLDs) are co, me, org, ltd, net, plc and sch - for commercial enterprises, individuals, non-commercial organisations, limited companies, public limited companies, internet service providers and schools respectively, and there are others such as ac, gov, nhs, police and mod. For more information on SLDs go to www.nic.uk and select Second Level Domains from the menu.

Nominet has a membership scheme to allow third parties to act as domain name agencies for enterprises and the general public. Caz Limited is a paid-up member of Nominet which means we can do this.
US domain name registration

The top level domains (TLDs) that don’t have a country code are American but most people treat them as global. The US authorities have licensed a number of private enterprises both within the US and outside to manage these TLDs which include com, net, org, info, biz, etc.

Examples of registrars in the US are Network Solutions and Register.com. Outside the US we have joker.com in Germany and even France Telecom.

At Caz Limited we have an account with the registrar Network Solutions. We try to keep all our US domains under one roof in order to simplify management (they have the best management interface at the moment). However some domain agencies make it difficult to transfer between registrars, so we have to do the best we can.
Registering a domain name

Domains can be registered directly through a registrar or using an agent (like Caz Limited). With the DIY approach you have to manage the technical issues of the domain name service (more on this later), ensure that the domain name is properly renewed every two or three years and not fall foul of scams relating to domain name renewal - the latter are all too frequent.

UK domain names expire after two years unless positively renewed. We renew all the UK domains under our control by default. If we reckon that a domain has had its day, then we discuss this with you before letting it go.

US domains (eg com, net) may be registered for between one and nine years. We usually choose three years.
Multiple domains

For UK customers, it makes sense to have both a dot com and a dot co dot uk (or whatever is appropriate in the global and national stakes). This domain name is mapped onto the same website.

For commercial reasons, it may be appropriate to have more than one domain name ie not just mycompany.com and mycompany.co.uk but also agoodcommercialname.com. One reason for doing this may be to prevent cyber squatting - the practice of some individuals and organisations for taking similar names to yours with the express intent of capturing your business. One of our clients has had this problem, so we believe the threat is real but shouldn’t be overstated. There are also various scams running where people threaten to take a name or indicate that ’someone has approached them to take a name’ but offer it to you instead (for a price). Sometimes you may have to treat this threat seriously, but the chances are we can register the name for less and, if need be, quickly.
How do people find your website or send you email?

The answer is by using a giant address book called the domain name service which keeps tabs on all the domain names and numbers on the Internet. This service is provided by computers called DNS servers. However, DNS is also used to underpin the logical structure of computers on local area networks as well, particularly for Windows 2000 and later operating systems.

The only time DNS will become important to you is when you move your website or mail between ISPs.

When you put in a web address into your browser, your computer looks up the name in the nearest DNS server. The ‘nearest’ has either been set by your computer system administrator or your ISP has made it automatically look at its own - every ISP has at least two DNS servers. If the address cannot be resolved (ie found) then the DNS server looks further upstream (to the DNS server it’s been set to look at) and so on until the root DNS server is found - this will have the correct IP address for a domain name. Once found, a DNS server (wherever it is in the chain) will cache (ie store) the name and matching address for (usually) 48 hours. This means that if it gets another query for the same domain name, it doesn’t have to go looking.

The cached record in the DNS server has a Time To Live (TTL) counting down from the aforementioned 48 hours and besides some big DNS servers only update twice a day. Since we don’t know how many DNS servers are sitting between the requesting computer and the top of the tree, it’s impossible to know how long it will be before a transferred website or mail service will be off-air because the cache time on each DNS server is unknown.
The last leg

Once the visitor to your website has arrived at our servers our DNS directs them to it using the www part of the domain name which, in Internet-speak, is called the host name. Note that www is just a convention: one can have anything (or nothing) but since most visitors are used to www it’s not particularly sensible to change.

Email goes to a separate mail server, most commonly redirected to one on your premises (by the IP address alone, so friendly names required). This requires you to have SMTP (Simple Mail Transfer Protocol) mail server software on your server hardware. This mail server resolves user names (eg the john in john@mycompany.co.uk) and puts the mail in their mailbox.

We can also send your email to POP (Post Office Protocol) mailboxes from which you collect it but this is a much less efficient way of operating.

This entry was posted on Saturday, August 2nd, 2008 at 4:08 pm and is filed under Webmaster Info. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.