Transcript How to find your IP Address?

Internet
Addressing
• When your computer is on the Internet,
anything you do requires data to be
transmitted and received.
• For example, when you visit a web site, such
as google.com, data is transmitted to your
computer in order to load the content of the
web page.
• The server where google.com is located needs
to know where to send the data.
• Network layer
• When you connect to google.com, it receives
your IP Address and then knows where to
send the data.
• Every machine on the Internet has a unique
identifying number, called an IP Address.
• Without a unique IP address on your machine,
you will not be able to communicate with
other devices, users, and computers on the
Internet.
• You can look at your IP address as if it were a
telephone number, each one being unique
and used to identify a way to reach you and
only you.
• A typical IP address looks like this:
• 216.27.61.137
• To make it easier for us humans to remember,
IP addresses are normally expressed in
decimal format as a "dotted decimal number"
like the one above. But computers
communicate in binary form.
• Look at the same IP address in binary:
• 11011000.00011011.00111101.10001001
• There are three common ways in which IP
address can be represented.
• There is the binary notation which uses base
two number system to represent numbers. For
ex –
11011000.00011011.00111101.10001001
• There is the decimal notation which uses base
ten number system to represent numbers. For
ex – 254.202.52.23
• There is the hexadecimal notation which uses
the base sixteen number system to represent
numbers. For ex - E3:F4:C8:A5
• The four numbers in an IP address are called
octets, because they each have eight positions
when viewed in binary form. If you add all the
positions together, you get 32, which is why IP
addresses are considered 32-bit numbers.
Since each of the eight positions can have two
different states (1 or 0) the total number of
possible combinations per octet is 28 or 256.
So each octet can contain any value between
0 and 255. Combine the four octets and you
get 232 or a possible 4,294,967,296 unique
values!
• Out of the almost 4.3 billion possible
combinations, certain values are restricted
from use as typical IP addresses. For example,
the IP address 0.0.0.0 is reserved for the
default network and the address
255.255.255.255 is used for broadcasts.
• Every IP address that is exposed to the public
Internet is unique. In contrast, IP addresses
within a local network use the same private
addresses; thus,
• a user's computer in company A can have the
same address as a user in company B and
thousands of other companies. However,
private IP addresses are not reachable from
the outside world.
• IP address classes
• These IP addresses can further be broken
down into classes. These classes are A, B, C, D,
E and their possible ranges can be seen in
Figure 2 below.
• Class
Start address
Finish address
• A
0.0.0.0
126.255.255.255
• B
128.0.0.0
191.255.255.255
• C
192.0.0.0
223.255.255.255
• D
224.0.0.0
239.255.255.255
• E
240.0.0.0
255.255.255.255
• IP address classes, Network and Host
• Private Addresses
• There are also blocks of IP addresses that are
set aside for internal private use for
computers not directly connected to the
Internet. These IP addresses are not supposed
to be routed through the Internet, and most
service providers will block the attempt to do
so. These IP addresses are used for internal
use by company or home networks that need
to use TCP/IP but do not want to be directly
visible on the Internet. These IP ranges are:
Class Private Start Address Private End Address
A
10.0.0.0
10.255.255.255
B
172.16.0.0
172.31.255.255
C
192.168.0.0
192.168.255.255
If you are on a home/office private network
and want to use TCP/IP, you should assign your
computers/devices IP addresses from one of
these three ranges. That way your
router/firewall would be the only device with a
true IP address which makes your network more
secure.
• If you look at the table you may
notice something strange. The range
of IP address from Class A to Class B
skips the 127.0.0.0-127.255.255.255
range. That is because this range is
reserved for the special addresses
called Loopback addresses that have
already been discussed above.
• The Address Itself (Loopback Address)
• Out of these addresses there are 3 special ranged
that are reserved for special purposes. The first is
the 0.0.0.0 address and refers to the default
network and the 255.255.255.255 address which
is called the broadcast address. These addresses
are used for routing, which will not be covered in
this tutorial. The third address, 127.0.0.1, is the
loopback address, and refers to your machine.
Whenever you see, 127.0.0.1, you are actually
referring to your own machine. That means if you
clicked on this link, http://127.0.0.1, you are
actually trying to connect to your own computer,
and unless you have a web server running, you
will get a connection error.
• Default Network: The special network 0.0.0.0 is
generally used for routing.
• Class A: From the table above you see that there are
126 class A networks. These networks consist of
16,777,214 possible IP addresses that can be assigned
to devices and computers. This type of allocation is
generally given to very large networks such as multinational companies.
• Loopback: This is the special 127.0.0.0 network that is
reserved as a loopback to your own computer. These
addresses are used for testing and debugging of your
programs or hardware.
• Class B: This class consists of 16,384 individual
networks, each allocation consisting of 65,534 possible
IP addresses. These blocks are generally allocated to
Internet Service Providers and large networks, like a
college or major hospital.
• Class C: There is a total of 2,097,152 Class C
networks available, with each network
consisting of 255 individual IP addresses. This
type of class is generally given to small to midsized companies.
• Class D: The IP addresses in this class are
reserved for a service called Multicast.
• Class E: The IP addresses in this class are
reserved for experimental use.
• Broadcast: This is the special network of
255.255.255.255, and is used for broadcasting
messages to the entire network that your
computer resides on.
Static and Dynamic IP
Network infrastructure devices such as servers,
routers and firewalls are typically assigned
permanent "static" IP addresses. The client
machines can also be assigned static IPs by a
network administrator, but most often are
automatically assigned temporary "dynamic" IP
addresses via software that uses the "dynamic
host configuration protocol" (see DHCP). Cable
and DSL modems typically use dynamic IP with a
new IP address assigned to the modem each
time it is rebooted.
• Logical vs. Physical
An IP address is a logical address that is
assigned by software residing in a server or
router (DHCP). In order to locate a device in
the network, the logical IP address is
converted to a physical address by a function
within the TCP/IP protocol software (ARP).
The physical address is actually built into the
hardware (MAC address).
• IPv4 and IPv6 Addresses
• There are two flavors of IP Addresses that can
be used on a network.
• The first, and the version that the Internet and
most routers are currently configured for, is
IPv4 or Internet Protocol version 4.
• This version uses 32-bit addresses, which
limits the amount of addresses to
4,294,967,296 possible unique addresses.
• Some of these addresses, about 290 million,
are also reserved for special purposes.
• IPv6 is going to solve a few major problems:
• IP address contains two parts. The first part is the
network identifier and the second is the host identifier
in that network. Not all the addresses in a specific
network are going to be used, which is very wasteful.
• The Internet is growing rapidly. Many organizations
have more than a single LAN, and wireless networks
are also going to be used more and more in the future.
• There is an increased usage in IP addressing in many
new areas. Not only computers can be connected to a
network, but also other electric devices can be
controlled using the SNMP protocol. (Mobiles)
• There are advantages of giving multiple addresses per
host, The problem - an increase in the number of
addresses in use.
• All of these problems are solved in IPv6
because the new address in IPv6 is
constructed from 128 bits instead of 32 bits
and it is going to increase the address space
by 2128.
• IP addresses change significantly with IPv6.
IPv6 addresses are 16 bytes (128 bits) long
rather than four bytes (32 bits). This larger size
means that IPv6 supports more than
• 300,000,000,000,000,000,000,000,000,000,00
0,000,000 – 38 0’s
•In the coming years, as an increasing
number of cell phones, PDAs, and other
consumer electronics expand their
networking capability, the smaller IPv4
address space will likely run out and IPv6
address become necessary.
IPv6 addresses are generally written in the
following form:
hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:h
hhh
"IP Conflict"
There are some guidelines to how IP address can appear,
though. The four numbers must be between 0 and 255,
and the IP address of 0.0.0.0 and 255.255.255.255 are
reserved, and are not considered usable IP addresses. IP
addresses must be unique for each computer connected to
a network. That means that if you have two computers on
your network, each must have a different IP address to be
able to communicate with each other. If by accident the
same IP address is assigned to two computers, then those
computers would have what is called an "IP Conflict" and
not be able to communicate with each other.
• How to find your IP Address?
• Windows -- Though you can click through the
user interface to find your network interface
settings, one quick way to find your IP address
is to open the Command Prompt application
from Accessories and enter this command:
ipconfig