About Domains
By Tshepo Khoza
What is a domain?
One of the best ways to describe a domain is this: A Domain name is to a website what a street address is to a house. Every Website needs one if it is to exist in cyberspace and to be found by visitors. One can say that all houses have addresses: in fact it is a common factor between a shack in a squatter camp and a mansion in a Golf estate. Some people even refer to domains as web addresses.
Why do we use Domain names?
A lot of people who use the Internet frequently would not know what an IP address is and would have trouble remembering all the IP addresses that exist out there. It is easier for humans to remember a concise word or even a few of them than it is to recall numbers. For example, many of us are familiar with www.yahoo.com or www.dkweb.co.za. It would be more of a hassle for us to have to remember 204.71.200.74 than to say "www.yahoo. com ". Therefore domain names make it easier for us to recognise web addresses.
The number 204.71.200.74 (IP address-Internet Protocol address) refers to the same host as the URL (Uniform Resource Locator- that is http://www.yahoo.com ) but since names are easier to work with than strings of numbers, a DNS (Domain Name System) was developed to translate between meaningful host ames and IP addresses.
The DNS Hierarchy
The Domain Name System (DNS) is basically a large database which resides on various computers and it contains the names and IP addresses of various hosts on the internet and various domains. The Domain Name System is used to provide information to the Domain Name Service to use when queries are made. The service is the act of querying the database, and the system is the data structure and data itself. The Domain Name System is similar to a file system in Unix or DOS starting with a root. Branches attach to the root to create a huge set of paths. Each branch in the DNS is called a label. Each label can be 63 characters long, but most are less. Each text word between the dots can be 63 characters in length, with the total domain name (all the labels) limited to 255 bytes in overall length.
The adjacent image decribes the hierarchy of the DNS system (click on the image to enlarge it).
DNS names are assigned through the Internet Registries by the Internet Assigned Number Authority (IANA). The domain name is a name assigned to an internet domain. For example, mycollege.edu represents the domain name of an educational institution.
Top level domains (TLD) contain other domains that represent organisations and companies or even countries (eg .com, .net, .za.)
The names microsoft.com and 3Com.com represent the domain names at those commercial companies. Naming hosts within the domain is up to individuals administer their domain.
The following picture illustrates the use of Top Level Domains (TLD):
The TLD for South Africa is .za. In addition to this we have the second level domains such as .ac.za (Used by Universities) and .co.za (Used by companies in South Africa)
e.g dkweb.co.zaDNS Names are unique. The path names are often (if not always) separated by a full stop for example dkweb.co.za which describes a corporation (dkweb) that funtions as a corporation(or company) (.co) in South Africa (.za)
DNS in Action
DNS maintains a record of which IP address corresponds to which domain name. Thus it is possible for dkweb.co.za to move to a different IP address while enabling users to still reach it by entering http://www.dkweb.co.za in their browsers address bars. DNS is implemented on the Internet through special servers called name servers.
When you enter a Uniform Resource Locator (URL) into your browser, your PC sends a request to the local name server to have the URL translated into an IP address. This local server is typically provided by your Internet Service Provider (ISP) such as Mweb or Telkom or Dot Khoza Website Development CC, or it might be on your company's network.This name server would typically know the IP address for the URL you sent. but if it does not know it, it woulsd send a request for name resolution out to the Internet. This request would begin at the root (.com) where it would get the name servers to which the said URL corresposnds. Your local name server would then interact with the name server to get the URL for you and display it on your browser when it is found.
Acquiring a Domain Name
Having a domain name enables anyone to provide others with an easy-to-remember address your your Website. If you don't have your own domain name, you might have to privide a URL that contains an IP address or even your ISP's address. how many companies do you know who still use companyname@mweb.co.za in their e-mail addresses? such companies are usially not taken seriously by their peers. With your own domain name, you can shorten the long URLs and customise it to what you want it to be and that suits your business.
To get a domain name, you can go through your ISP, although not all ISPs offer this service. For .co.za domains you could even apply for it yourself; but the administrators of .co.za recommend that you use an ISP. This is becaus ethey require the names of the nameservers and IP addresses with your application. This is information that normally an ISP would have.
You can also apply here for a domain name.
This is the first article to appear in the www.dkweb.co.za website.
Tshepo Khoza is the Managing Director of Dot Khoza Website Development CC. He can be contacted at info@dkweb.co.za