What's in a name?

By: Sean Hearne

When you surf the net or send an email message, you are using the concept of domain names. For example, the Universal Resource Locator (URL) http://www.tssg.org contains the domain name tssg.org, as does the e-mail address fake_user@tssg.org. Human readable names like 'tssg.org' and 'yahoo.com' are easy for people to remember, but they are not machine readable. PCs use names called IP addresses (Internet Protocol addresses) to refer to one another and every computer on the Internet has a unique IP Address. The format of an IP address is a 32-bit numeric address written as four numbers separated by full stops. Each number can be zero to 255. For example, 209.61.157.249 is an IP address.

Every time you use a domain name, you use the Internet's Domain Name Service (DNS) to translate the human readable domain name such as 'Yahoo.com' into the machine readable IP Address. Converting domain names to IP addresses is called name resolution and this conversion is performed by DNS servers. A DNS server acts like a large telephone directory, which associates a domain name with the appropriate IP number. So think of the IP address as something similar to a phone number: When someone calls http://www.tssg.org, your Internet Service Provider (ISP) looks at the DNS server, and asks "how do I contact tssg.org?". The DNS server responds that it can be found at: 209.61.157.249. During a day of browsing and emailing, you might access the domain name servers hundreds of times!

A Server has a static IP Address that does not change very often. A home machine that is dialling up through a modem often only has an IP Address that is assigned by the Internet Service Provider (ISP) (eircomnet, oceanfree, IOL, etc.) when you dial in. In this way an ISP only needs one IP Address for each modem it supports, rather than one for every customer.

If you are working on a Windows 95/98 machine, you can view a large amount of Internet information for your machine with the winipcfg program, including your current IP address and hostname. To run this program, select the run option on the Start menu, type "winipcfg" into to the box and click on the OK button.

Alternatively if you have a Windows 2000/XP machine, you can use the "ipconfig" program.
Every domain name has a suffix that indicates which top-level domain (TLD) it belongs to. There are several hundred TLDs. The most popular domain suffix today is .com. Some 30 million web sites carry this label at the end of their addresses. TLDs such as .com, .org and .net as well as the recently added .name .biz and .info are open to everyone to register. Others such as .edu and .gov have restricted registration.

Two letter TLDs such as .ie and .uk are called country code TLDs (ccTLD) and these belong to countries and geographical regions. Each country sets its own standards. Some country code TLDs are carefully managed and fairly strict rules apply as who may have what name - the .ie domain would be an example of one of these. Others, such as .tv (country code TLD of the south pacific island of Tuvalu) have more relaxed rules, as is the case with .com registration.
A new .eu TLD, which the EU hopes to create for companies and individuals in member states is in the process of being established. The European Commission is currently reviewing submissions from organisations wishing to operate the domain name registry of this new domain. Eureto, an All-Ireland organisation, is currently one of the main bidders for this. EU domain names should be available for registration later this year.