All you need to know about IP address
If you aren't sure what IP address is, IP
(Internet Protocol) address is a unique address that identifies a
computer or a device on the Internet. It contains 32
bits or 4
bytes (octets) and is
written in four sets of decimal numbers separated by a period (or
dot) in between. Each set of decimal numbers represents a byte (i.e. 8
bits) and can not exceed 255, that is when all the eight bits are 1 (or 11111111). Example of IP address: 202.60.80.1
An IP
address
is comparable to a telephone number that uniquely identifies an
individual or a business on the telephone network.
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==>> The anatomy of IP address
Every computer or device on the Internet is part of a network
(e.g. ISP, corporate, or home network). That's why IP address body
(i.e. xxx.xxx.xxx.xxx where x is a decimal number) consists of
network identity (ID) and host (i.e. node/device) ID. A subnet
mask value which resembles an IP address is usually given along
with an IP address to help identify which part of the address
refers to network ID or host ID. Subnet is logical grouping of
hosts in a network that functions to segregate traffic.
In a class A IP address, the first byte refers to network ID
and the last three bytes refer to host ID. In a class B IP
address, the first two bytes refer to network ID and the last two
bytes refer to host ID. In class C IP address, the first three
bytes refer to network ID and the last byte refers to host ID.
Class A IP addresses are used by very big networks, class B by
medium to large networks, while class C by small networks.
| |
From |
To |
Default subnet mask |
| Class A |
0.0.0.0 |
127.255.255.255 |
255.0.0.0 |
| Class B |
128.0.0.0 |
191.255.255.255 |
255.255.0.0 |
| Class C |
192.0.0.0 |
223.255.255.255 |
255.255.255.0 |
Example, if your computer IP address is 192.168.1.3 (a class C
IP address), it must belong to a network (LAN) with this network
address
192.168.1.0 and its host ID is 3.
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Your IP address currently is 18.217.237.68
When your computer (be it a desktop PC, laptop/notebook,
netbook, tablet, handheld/PDA,
or smart phone) accesses the Internet, it has an IP address that
is assigned to it by your ISP or a broadband router in your
home or company network. IP address is different with MAC address. A MAC
address or physical address was assigned to a device by its
manufacturer and stays the same during its lifetime while IP
address depends on the network or service provider through which
your computer or device gets an Internet connection.
For example, if you use Windows XP, to check your IP address,
do one of the following:
1) double-click your Internet connection icon on the taskbar and
click the Details tab.
2) open the Command Prompt window and type this command :
ipconfig
or ipconfig /all. You can go to the Command Prompt through
Start > All Programs > Accessories > Command Prompt. [To
find Command Prompt in Windows Vista or Windows 7, just click
Start button and type cmd in the search box and press Enter.]
3) go to Network Connections folder, click on your Internet
connection name, and see your IP address on the Details pane on
the bottom left of the folder. You can go to the Network
Connections folder through Start > Connect To > Show all
connections or through Control Panel. [In Windows Vista or Windows
7, right click a connection icon on the taskbar/system tray,
select Network and Sharing Center. On the left pane, select
Manage network connections to open Network Connections
folder. Right click an active connection, select Status, and click
Details.]
This article provides
a more detailed interpretation of your IP address.
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When your computer connects to your
ISP, your ISP assigns an IP address to it. In the case of
dial-up access over telephone line or broadband access (e.g. DSL or
cable modem) using PPPoE/PPPoA
that requires log-in, your computer will get a different IP
address each time it connects to the ISP and makes an Internet connection
through it. This address
is called dynamic IP address. The IP address is assigned by a
DHCP server at your ISP.
This this the most common case since every ISP has limited IP addresses
stock. On the other hand, using an always-on broadband connection, your
computer is usually given the same IP address all the time by the
ISP. This address is called static IP address.
Dynamic IP address is assigned to your computer by a
broadband router (or residential gateway) if your computer is on a LAN
(home or office network) and
accesses the Internet through a broadband router. But this address
is for internal use only, it gets converted to a public IP address
when communicating over the Internet. Dynamic IP address assignment is
handled by a DHCP server at the router. The DHCP server can be set to reserve an IP address
for a computer during a connection or change it periodically at a predefined interval.
The router also handles the network address translation (NAT),
i.e. converting private IP address assigned by the DHCP to a
public IP address assigned by the ISP.
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