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Part One
ABCs of Domains
by Sharlee Plett
What is a Domain Name?
A domain name is a unique Internet address name that has been registered
for use in the Internet's
Domain Name System.
A domain name is always composed of two words or phrases, separated
by dots, like this:
myname.com yahoo.com.
learn.net w3.org
The first part of the domain name is the domain itself. In myname.com,
"com" is the domain. The second part of the domain name is a unique
name, which forms a sub domain in that particular domain. In myname.com,
"myname" is the sub domain in the "com" domain. The two parts taken
together make up the domain name.
Sub domain Domain
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myname.com
To help understand how the names relate, you could read the dot between
the two parts as the word "in"- myname.com could be read as follows:
Sub domain in Domain
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myname . com
The domain part of the domain name is often called the top-level domain
or first level domain. The unique name part of the domain is sometimes
called the second-level domain name, sub domain or base domain name.
The rule is that every sub domain name in a particular domain must be
unique. Since there are many domains in which a name could be used to
form a sub domain, the names themselves are not unique. Only the two-part
domain name itself can be and must be unique. As an example, the name
"myname" could be part of all of the following domain names:
myname.com
myname.net
myname.org
myname.de
As you can see, each one of the above domain names is unique, but the
sub domain "myname" isn't unique.
What is a Domain?
Specific domains have been authorized for use in the official Internet
domain name system. The domains that are currently authorized are 2 to 4
characters in length. There are two broad categories of domains - generic
and country.
Generic domains are reserved for use for a particular type of activity
on the Internet. Examples of the generic domains include .com, .org,
and .net. They are often referred to as generic top-level domains
or "gTLD"s.
.com is for commercial or business use
.net is for network use
.org is for non-profit, non-commerical use
The following generic domains are special top-level domains and are often referred to as "sTLDs".
.edu is for 4-year colleges
.gov is for U.S. federal government agencies
.mil is for U.S. military organizations
.int is for International treaty organizations
Each country or territory in the world has its own country domain. These
are often referred to as country codes or "cc"s. The United Kingdom, for
example, uses .uk. France uses .fr, Denmark .dk, and so on.
Click here for a full list of country domains.
Some countries will preface their country codes with a generic domain such
as .com.uk.
What is a Canonical Domain Name?
When you own a
domain name, such as myname.com, you can create canonical
domain names with it. This is done by adding a name before your domain
name, followed by a dot. As an example, if you own the domain name
myname.com, you could create the following canonical domain names:
info.myname.com
contact.myname.com
about.myname.com
email.myname.com
You do not have to register canonical domain names. You only have to
register the domain name you are building a canonical name from. There
is no restriction on how many canonical names you can create with your
domain name.
Canonical names are often called sub domains or third-level domain names.
What is a URL?
URL stands for Uniform Resource Locator. A URL maps out the address,
exact location, file name and type of resource you are requesting from
a website so your computer system can find and display it correctly.
Here's an example of a typical URL:
http://www.darinswan.com/dchains/resourcesites.htm
A URL is organized in parts, separated by specific symbols such as right
slashes, dots or colons, in a very specific order. If you get the order
wrong or put in the wrong separators, or make a typing error on the name
of any of the parts, your computer system may not be able to locate the
resource you want.
Part 1: Transfer Protocol
This tells your computer system what type of information is going to be
located and transferred to your computer. It is always a word or
abbreviation followed by a colon and two right-slashes. Here are the
most common types:
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http:// |
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This stands for "HyperText Transmission Protocol" which is the standard format for the World Wide Web. |
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gopher:// |
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This is a text only format that was the precursor for the web. It is still in use on many websites - usually academic or government types. |
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ftp:// |
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This stands for "File Transfer Protocol" which is a file download format. It means that a file is about to be downloaded to your computer. If this is new to you, you should learn more about this before you use it. |
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news:// |
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This is a format for newsgroup information, which is like a bulletin board. |
Part 2: Host Name
The host name gives the address to the computer that is hosting or storing
the resource you want to find. It is organized in two sections and each
part of the host name is separated by dots. The host name is followed by
a right-slash to show that that's the end of the host name. In the
following example, the host name is in red text:
http://www.domains.sharlee.com/dchains/resourcesites.htm
The first section of the host name is the abbreviation for the network
service that is running on the hosting computer. There are many different
types of network services that a hosting computer can run. The most common
is www, which stands for World Wide Web - a network service that makes
files and information available to users on the World Wide Web. If you
type in a URL starting with "http://", you don't always have to type in
the network service abbreviation "www". This is because many computer
systems will automatically insert it for you. In the following example,
the network service prefix is in red text:
http://www.domains.sharlee.com/dchains/resourcesites.htm
ftp://ftp.domains.sharlee.com/dchains/resourcesites.pdf
The second section of the host name is the domain name and possibly a sub
domain name for the hosting computer.
The domain name is in red text:
http://www.sharlee.com/dchains/resourcesites.htm
The domain name and its sub domain is in red text:
http://www.domains.sharlee.com/dchains/resourcesites.htm
Part 3: Directory/Subdirectory
Part 3 of the URL tells the computer system which directory and/or
subdirectory (path) to look in to find the resource you want.
The directory and subdirectory names are separated and ended by the
right slash character.
In this example, the path isn't shown, and the computer system will
automatically default to the default directory and show the home page
for the website address: http://www.domains.sharlee.com/dchains/
In this example, the directory "dchains" is in red text:
http://www.domains.sharlee.com/dchains/doc1.htm
In this example, the directory "dchains" and the subdirectory
"resourcesites" are in red text:
http://www.domains.sharlee.com/dchains/resourcesites/doc1.htm
Part 4: File Name
Part 4 of the URL shows the file or document's name, followed by a dot,
followed by the standard abbreviation for the file type extension.
In this example, the file name is shown in red text:
http://www.domains.sharlee.com/dchains/resourcesites.htm
Files that are web pages usually end in .htm or .html. There are many
other extensions that are used on the web for file types like graphic
images, compressed files and so on. For some types of files, the file
extension isn't necessary.
Part 5: Parameters
If you use a search engine or click on some links on a website, you will see
part 5 of the URL. This is a series of characters that tell the computer
system where to look within a file to get the exact information you are
looking for. In the following examples, the parameters are in red text:
http://www.altavista.com/cgi-bin/query?pg=q &q=directory:bus&stq=10
http://www.instantweb.com/foldoc/foldoc.cgi?hostname
The parameter section begins with a symbol like ? or # and provides the
necessary search information in the characters that follow.
What is the Domain Name System?
The DNS or Domain Name System is simply a system that matches
domain
names with
IP addresses. This system makes it possible to locate a
website by its domain name instead of having to remember and type in
the 4 to 12 numbers of its IP address. As an example, when you type
yahoo.com in your browser, the domain name system fetches Yahoo's IP
address, which is 216.32.74.50 and connects you to the Yahoo website.
An IP address can have more than one domain name matched to it.
As an example, the IP address 216.32.74.50 could have both yahoos.com
and yahoo.com matched up to it.
What's your IP?
See what your current IP Address is.
What is an IP Address?
Every computer connected to the Internet has a numeric address
assigned to it. This number is called the Internet Protocol (IP) address.
You could think of this address as your computer's telephone number
on the Internet.
The IP address is made up of four numbers that are
separated by dots, like this: 216.32.74.50 or like this: 209.15.63.7.
Each of the four numbers can be 1 to 3 digits long.
Internet Service Providers (ISPs) purchase blocks of IP addresses,
which they assign to their customers. Each time you go online, your
ISP assigns you an IP address from their block of IP addresses.
You will usually be assigned a dynamic IP address, which changes
each time you go online.
When you set up a website with your ISP, your ISP sets up disk space for
you on their computer system. This is your webspace location on their
system. Then they assign your location a specific IP address from their
block of IP addresses. The IP address they assign will usually be
static IP address, which never changes.
If a website has a static IP address, you can type the website's IP
address in your browser's address or location instead of the website's
name. As an example, you can get to Yahoo's website by typing yahoo.com
or by typing 216.32.74.50. Either one will take you to Yahoo's website.
Click Here
and enter Yahoo's IP Number.
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