Page 11 - DCAP202_Fundamentals of Web Programming

Fundamentals of Web Programming

Notes
Example: The domain name microsoft.com represents about a dozen IP addresses.
Domain names are used in URLs to identify particular Web pages. For example, in the URL
http://www.abc.com/index.html, the domain name is abc.com. Every domain name has a suffix
that indicates which Top Level Domain (TLD) it belongs to. There are only a limited number of
such domains. For example:

Figure 1.1: Examples of Domain Names
Gov Government Agencies
Edu Educational Institutions
Org Organizational (nonprofit)
Mil Military
Com Commercial Business
Net Network Organizations
ca Canada
th Thailand

1.3.2 Host Name

A name is a label that is used to distinguish one thing from another. A person's name, for
instance, comprises a set of alphabetic characters that allows a person to be individually addressed.
Computers are also named to differentiate one machine from another and to allow for such
activities as network communication.
A hostname is a label that is assigned to a device connected to a computer network and that is
used to identify the device in various forms of electronic communication such as the World
Wide Web, e-mail or Usenet. Hostnames may be simple names consisting of a single word or
phrase, or they may have appended a domain name, which is a name in a Domain Name System
(DNS), separated from the host specific label by a period (dot). In the latter form, the hostname
is also called a domain name.

Did u know? If the domain name is completely specified including a top-level domain of
the Internet, then the hostname is said to be a Fully Qualified Domain Name (FQDN).

The true "name" a computer needs in order to communicate on a network is actually a set of
numbers. The original computers connected as the Internet used small integers as the host
number. For TCP/IP, the main protocol used by the Internet, each computer has a network IP
address that follows a specific set of rules to assure its uniqueness and validity. (Additionally,
port numbers further specify the access points for particular services on a computer).

1.3.3 Domain Name System

The DNS translates Internet domain and host names to IP addresses. DNS automatically converts
the names we type in our Web browser address bar to the IP addresses of Web servers hosting
those sites.
An often-used analogy to explain the Domain Name System is that it serves as the phone book
for the Internet by translating human-friendly computer hostnames into IP addresses.

Example: The domain name www.example.com translates to the addresses 192.0.43.10
(IPv4) and 2001:500:88:200::10 (IPv6).

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