LIS 525 - Domain Names
A domain name
is a name that identifies one or more IP
Domain names are used in URLs
as well as in e-mail addresses.
For example, in the URL
the domain name is uwo.ca;
other elements illustrated are the protocol (http://),
the host name (www),
and the path (/univsec/handbook/).
Every domain name has a suffix
(such as .gov, .edu, or .ca)
that indicates which top level domain (TLD)
it belongs to.
There are a limited number of TLDs,
although the number has recently been increased.
The part of the domain name before the dot
is the Second Level Domain (SLD).
Because IP addresses are used to route data
through the Internet,
every Web server requires a Domain Name System (DNS) server
to translate domain names into IP addresses.
the host name plus domain name www.uwo.ca
translates into 126.96.36.199.
If one DNS server doesn't know how to translate a particular
it asks another one, and so on,
until the correct IP address is returned.
Before checking domain names on other servers,
a computer may check a local list for IP numbers.
For example, Microsoft TCP/IP for Windows looks at a plain-text file
(typically found in windows\system32\drivers\etc\),
which the user can edit to provide customized aliases
or to block access to certain servers.
Domain names and host names are used
because people can more easily recognize and remember meaningful
than long strings of numerals,
and because they can be reassigned to new machines
(with different IP addresses).
Getting your own domain name has advantages and disadvantages.
- Easier for users to remember
(such as instruct.uwo.ca/~craven)
- More impressive
(looks less like a personal site)
- Transportable to another hosting service
- Must be registered with appropriate service,
normally for a small yearly fee.
- The name you want may already be taken;
you may have to pay a lot (or sue)
to obtain it.
- You may lose the domain name
unexpectedly because of registrar incompetence.
- DNS records must be maintained on a server.
Letters and numbers are valid characters in a Web address,
as are hyphens except at the beginning or end.
Special characters may not be used
(apart from the period,
which has a special meaning).
the maximum number of characters is 256 (including the TLD),
but individual registration services usually impose lower
such as 25 or 67 characters.
Applicants for domain names must ensure
that they have the right to use the domain names
and that the registration or use of the domain name
does not violate intellectual property or other rights,
is not defamatory,
and does not contravene any applicable laws.
Registration services may also require
that the name be put into service
as a functional and reliable Internet address,
that registration not be used
for hoarding or for excessive protection of trademarks,
or that the use is appropriate to the scope of the TLD.
In the past,
to have a host name,
a computer had to have a fixed IP address.
Thus, users of cable modem and dialup services,
with dynamically assigned IP addresses,
for example, had difficulty in running their machines as
But a new service called dynamic domain name system
actively tracks changes to a subscriber's dynamic IP address.
The query first goes to the dynamic DNS server
which hands out the destination's current address.
Some Guidelines for Choosing a Domain Name
- Choose an appropriate top-level domain or domains.
- Try for a variant of the name of your service
or Web site.
- Avoid names that are too narrow in scope
(e.g., the name of a short-term project
or of one event).
- Use Web-based wizards
or other tools,
to look for unclaimed domain names
that match key words.
- Avoid trademarks
(even your own name, if it is someone else's trademark).
- Don't use a name that is too long.
- Avoid made-up words and alternate spellings
(they can be annoying and hard to remember),
unless they are well established
(e.g., the name of your company).
- Use at least one reasonably rare word
(you have a better chance that the name is not already taken).
- Avoid top-domain-like names
(this can create problems with name resolution).
- Don't use an embarrassing name
or a name that may antagonize the wrong people.
- Don't use numeric digits at the beginning of the name
- Don't use non-alphanumeric characters.
Most of them don't work over the Internet.
Hyphens and underscores are technically OK,
but may be difficult for users to remember correctly.
A name should never begin with "xn--",
which is reserved for encoding
Internationalized Domain Names.
- Don't expect case to be preserved.
- For a large company,
consider registering many variant forms
and names of products,
to avoid their use by competitors, critics,
and purveyors of goods
with which the company does not wish to be associated.
For More Information
Links and Resources
- Canadian Internet Registration Authority. 2003.
CIRA - Canadian Internet Registration Authority.
("...a not for profit Canadian corporation
that is responsible for operating the .ca Internet country code
Top Level Domain".
Includes links to authorized registrars
for the .ca top-level domain.)
- Core Internet Council of Registrars. 2007.
CORE - Welcome to CORE.
("...a not-for-profit membership association of Internet
- Internet Assigned Numbers Authority. 2007.
IANA Home Page.
("Dedicated to preserving the central coordinating
of the global Internet for the public good.";
links to domain name services
and other information.)
- Internet Corporation for Assigned Names and Numbers. 2007.
ICANN - Internet Corporation for Assigned Names and Numbers.
("...the non-profit corporation that was formed to assume
responsibility for the IP address space allocation,
protocol parameter assignment, domain name system management,
root server system management functions
previously performed under U.S. Government contract
by IANA and other entities".)
- Network Solutions. 2007.
Domain Names, Domain Name Registration and Web Hosting |
- Canadian Internet Registration Authority. 2003.
Cira - Canadian Internet Registration Authority.
(Use the "WHOIS" form
to find information on .ca domain names.)
- IPAddressGuide.com. 2007.
IP Address Guide | Ping | Traceroute | DNS Lookup | CIDR | Geolocation |
(A collection of Web-based tools.)
- Name.Space. 2003.
Web-based WHOIS + NSLOOKUP by Name.Space.
(Gets information about a domain name
or translates between domain names and IP addresses.)
- Perry, R.S. 2007.
DNS tools, DNS hosting tests, WHOIS, traceroute, ping,
and other network and domain name tools.
(About 20 different Web-based tools.)
News and Commentary
Last updated October 26, 2007.
This page maintained by
Prof. Tim Craven
E-mail (text/plain only): firstname.lastname@example.org
Faculty of Information and
University of Western
Canada, N6A 5B7