One of the requirements of every communication network is an addressing system for each
node. Every individual unit or node in a communication system should have a unique
identifier. Consider the global telephone network for instance. Every phone in the whole wide
world connected to the telephone network has unique number associated with it. For
instance 1 269 387 3592 is assigned only to one phone in the world – the one in my office.
When someone dials this number from anywhere in the world, only my phone rings. Such
unique identifiers are necessary for successful communication. Imagine the confusion, if
multiple phones were assigned the same phone number?
In a computer network, it is necessary for each computer unit to have a unique identifier or
address. On the Internet, each computer is identified by a set of numbers known as the IP
address of the computer. (IP stands for Internet Protocol. The addressing conventions were
defined in TCP/IP). For example, the IP address of WMU’s network computer is
which looks almost a like a phone number. When a message is sent to someone with an
account at WMU, the network is able to know the computer and its location from its IP
address and route the message to WMU. The organization that allocates and manages IP
addresses globally is The Internet Corporation for Assigned Names and Numbers (ICANN). It is
a non-profit corporation headquartered in California and is responsible for the coordination
of the global Internet's systems IP address identifiers and, domain names.
As the number of computers connected to the Internet increased, it became harder to keep
track of the numerous IP addresses. When the number of telephones increased, a telephone
book was created to record the names of subscribers and their phone numbers. Such a
system was developed for IP addresses and is known as the Domain Name System
(DNS).Instead of creating a databases like a phonebook that users can look up, DNS assigned
easy to remember names to the IP addresses of network computers. For instance, the IP
address of CNN’s computer is CNN computer’s IP address was assigned a
domain name Users don’t have to know the IP address of CNN to access CNN;
they just need to remember the domain name which is easier.
To access the CNN website, we type in in our browser. When this information
goes to WMU’s network computer, it looks up a database of all domain names and IP
addresses (much like a telephone book) and routes our request to the IP address
corresponding to Who maintains the up to date database of all domain names
and corresponding IP addresses? A DNS name server is a server that stores this information
and responds with answers to queries from other network computers.
Domain names are not randomly assigned to computers but is a hierarchical distributed naming
system. A domain name consists of one or more parts orlabels, that are separated by dots. For
The right-most label conveys the top-level domain (TLD). For example the top level domain of is ‘edu’ and indicates that the computer belongs to an educational
institution. Some of the other top level domains are: com (commercial computers), gov
(government computers), net (telecommunication company computers), org (non-profit
organization computers). Please note that this classification according to the type of
organization is not strictly followed now. More TLDs have been designated in recent years to
meet the demand - biz, info, name, us, cn, and more recently xxx.
With the internet becoming more global, ICANN appended an international country label to
domain names such (United Kingdom), au (Australia), in (India), ml (Malaysia), hk (Hong
Kong). For example, the domain name of BBC is
Although ICANN oversees the administration of IP addresses and domain names, ICANN
authorizes and accredits private organizations and entities, known as domain name registrars,
to sell domain names to the public on a first-come-first-served basis and to update the domain
name registries. Today there are over 500 domain name registrars competing for this business.
The biggest registrar today is
Let us say that we are creating a website for a company called Kalamazoo Taxi Service. You
want the website to have a name that will easily be associated with the company and not
difficult to remember. So we choose a domain name for the company
Then we visit a domain name registrar like and check if this name has been
bought by someone else and is available for purchase. If it not, we try, or or any other TLD that is available. Let us say that is
available. We can then register that domain name for one or more years and pay
for it.
Let us say, we create the HTML documents containing information about Kalamazoo Taxi
Service that we want to publish on the web. This is only the first step to publishing the
website. The HTML documents we created will remain only in our PC until we upload these
documents into a network computer or server connected to the Internet 24/7. We do use our
PCs to connect to the Internet but we need a more stable connection if we want people to be
able to access our information any time. Hence, we need a web hosting service that allows us
to make our website available to the public 24/7. Web hosts are companies that provide
space on their server for their clients’ use. These servers have their own IP addresses. We sign
up for an account with a web host who will charge a monthly fee for ‘hosting’ our HTML
documents (approximately $4-10 per month). We also inform the web host the domain name
we have registered for our website. The webhost will then make an entry in the domain
registry that our domain name is associated with their IP address and our HTML documents
are hosted in their server. Now whenever anyone types in our domain name in their browser,
they will be directed to the IP address of our web host and to our account with them.
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