BOOT CAMP 169 (05/04//01)
DOMAIN NAMES AND THE INTERNET
Most of us have a basic grasp of how telephone numbers work
and even postcodes make some sort of sense, but the system of domain names and
web 'addresses' used for sending and receiving email and accessing information
on the Internet causes a great deal of confusion, even to seasoned PC
Much of it has to do with the speed at which the Internet has
developed. Unlike more traditional forms of communication, which have been
around for a century or more, the Internet -- as a mass-market technology -- is
barely ten years old, we've barely had a chance to get used to it and it is
steeped in seemingly impenetrable jargon. Over the next few weeks we'll try and
make some sense of it and show how easy it is to stake your claim on a piece of
the information superhighway – even if it's only the hard shoulder -- by
registering your own domain name, and setting up your own web site.
We'll begin with a short (promise…) history lesson, so please
be patient if you know this already, and apologies for all the acronyms, but
that's the nature of the beast… The Internet started out as a US military-funded
project in the late 1960s called the Advanced Research Project Agency Network
(ARPANET), a secure computer communications network that could survive a nuclear
attack. The idea was basically simple; instead of information passing between
distant computers going through a vulnerable central exchange the network is
made up of numerous semi autonomous nodes or 'host' computers, each one with
links to other hosts so that even if one link is broken messages can be
re-routed through another set of links. ARPANET spawned a number of civilian
offshoots including the National Science Foundation Network (NSFNET) and
Computer Science Network (CSNET), which were mostly used in educational,
scientific and commercial applications. Throughout the 1970s host computers in
other countries were added to the networks and by the early 1980s it had come to
be known as the Internet.
During the 1970s and 80 most of the technical standards and
protocols in use on the Internet today were developed and refined but the big
breakthrough occurred in 1984 when the number of host or 'server' computers
connected to the rapidly expanding network grew to more than 1000. Until that
point the server computers and countless desktop workstations connected to the
network, and the information they contained was identified by a unique string of
numbers, called an Internet Protocol or IP address. An IP address works a bit
like a like a postal address in that it is the Internet equivalent of a name,
house number, street, town and country, but it then goes on to specify the
location of a room in that house, a shelf on which books are kept, the title of
a book on the shelf, and the number of a page in that book.
As the network grew IP addresses made the system increasingly
cumbersome to use so the Domain Name System (DNS) was introduced. This
effectively replaced the numbers with an address made up of more memorable words
and names, called a Uniform Resource Locator or URL, the familiar
'www.anyname.com' system we all know and love.
The DNS is effectively the Internet's telephone directory but
there's no central registry as such, it's what's known as a distributed
database, which basically means that there are lots of computers or 'DNS severs'
connected to the Internet at strategic locations. When you enter a web address
or URL into your PC’s browser it sends out a request that's sent to the closest
DNS server. If the DNS server has had the same request before and it knows the
IP address for that URL it returns it to your browser, which then 'dials' up the
page. If the first DNS server doesn't recognise the URL, it passes the request
to another DNS server further up the line, and so on until the correct IP
address is returned.
That brings us on to the subject of Domain Names. An Internet
address or URL is divided into three 'levels', separated by the infamous 'dot'
or full stop. The Top Level Domain or TLD is the last two or three letters in an
address: com, .gov, .edu, .org, .net,
.uk etc. The .com TLD was originally intended for American companies and
multinational organisations but nowadays a .com address may be used by anyone,
(assuming it is available). TLDs are also used as country codes (uk for United
Kingdom, jp for Japan, fr for France and so on), or the nature or type of
activity an organisation or individual is involved in (.edu for education, .gov
government, .org non-profit making organisations like charities etc.).
The second level domain comes before the TLD and this can
either be a name – in the case of .com and .org addresses – or status, type of
business or activity. A URL ending in .co.uk indicates a UK based company,
.ac.uk and .sch.uk are reserved for UK schools and academic institutions and
.nhs.uk is used by National Health Service web sites.
The third level domain is the company, organisation or
individual's name, which is the bit we're interested in. If you have a web site
and you want people to find it easily then you need a memorable domain name.
Even if you don't have a web site you can still register your own domain name,
to prevent others from having it, or you can use it for email, you can even give
one to a friend or relative as a present, next week we'll show how it's done.
Next week – Domain names and the Internet, part 2
A group of computers sharing a common address or identity,
connected together by a network. Thus a desktop PC connected to the Internet via
an Internet Service Provider is part of that ISP's 'domain'
A computer – usually part of a wider network, like the
Internet -- that is accessed by one or more users at remote terminals
A 'location' in a network, either a computer or a peripheral
device, with it's own unique address
Windows is heavily reliant on a set of 'system' files for its
well-being. If a file becomes corrupted all sorts of bad things can happen, from
complete failure to error messages and odd behaviour. Windows 98 has an
unpublicised utility called the System File Checker, which can help engineers
and knowledgeable users to track down and automatically correct common problems.
It's worth running the SFC every now and again, especially on well-used
machines, and you never know, it may help to resolve a long-running problem,
however unless you know what you are doing it is a good idea to leave the
settings on their defaults. To start the program go to Run on the Start menu and
type 'sfc.exe' and click Start to begin the checking routine.