Page 16 - DCAP202_Fundamentals of Web Programming

Unit 1: Internet Basic

Host2Ip = myIPs.AddressList(0).ToString() Notes
Catch ex As Exception
‘Handle the error
End Try
End Function
Finally, although this approach works much better than just looking at REMOTE_ADDR, still
it’s far from a full proof solution, simply because it relies on the HTTP header information
which can be easily manipulated.

Self Assessment

Fill in the blanks:

10. The IP address could be used either for ........................... or authentication purposes.
11. Using the ........................... function we get a list of all the IP addresses the hostname resolves
to.

1.6 IP Address

An IP address is an identifier for a computer or device on a TCP/IP network. Networks using the
TCP/IP protocol route messages based on the IP address of the destination.
An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g.,
computer, printer) participating in a computer network that uses the Internet Protocol for
communication. An IP address serves two principal functions: host or network interface
identification and location addressing. Its role has been characterized as follows: “A name indicates
what we seek. An address indicates where it is. A route indicates how to get there.”

1.6.1 Network Part of IP Address

The format of an IP address is a 32-bit numeric address written as four numbers separated by
periods. Each number can be zero to 255.

Example: 1.160.10.240 could be an IP address.
Within an isolated network, you can assign IP addresses at random as long as each one is unique.
However, connecting a private network to the Internet requires using registered IP addresses
(called Internet addresses) to avoid duplicates.

1.6.2 Local Host Part of the IP Address

A localhost is, put plainly, the standard hostname given to the address assigned to the loopback
network interface. Translated into an IP address, a localhost is always designated as 127.0.0.1.
This may be overwhelming, so let’s look at what these things mean.
Hostname is the term for the label that is assigned to any device connected to a computer
network and is used to identify the device across the web. A hostname usually consists of a
single word or phrase and can be followed by a Domain Name System domain at the end. That
is, a website. Used this way, the hostname is called a domain name.

Example: An example of using a hostname this way would be: hostname.domain.

LOVELY PROFESSIONAL UNIVERSITY 9