IP Address
No doubt you've heard the term "IP address." Unless you're a techie, though, you may not have more than a shadowy notion of what an IP address actually is or how it works. Let's explore the concept.
An IP address is a fascinating product of modern computer technology designed to allow one computer (or other digital device) to communicate with another via the Internet. IP addresses allow the location of literally billions of digital devices that are connected to the Internet to be pinpointed and differentiated from other devices. In the same sense that someone needs your mailing address to send you a letter, a remote computer needs your IP address to communicate with your computer.
"IP" stands for Internet Protocol, so an IP address is an Internet Protocol address. What does that mean? An Internet Protocol is a set of rules that govern Internet activity and facilitate completion of a variety of actions on the World Wide Web. Therefore an Internet Protocol address is part of the systematically laid out interconnected grid that governs online communication by identifying both initiating devices and various Internet destinations, thereby making two-way communication possible.
An IP address consists of four numbers, each of which contains one to three digits, with a single dot (.) separating each number or set of digits. Each of the four numbers can range from 0 to 255. Here's an example of what an IP address might look like: 78.125.0.209. This innocuous-looking group of four numbers is the key that empowers you and me to send and retrieve data over our Internet connections, ensuring that our messages, as well as our requests for data and the data we've requested, will reach their correct Internet destinations. Without this numeric protocol, sending and receiving data over the World Wide Web would be impossible.
IP addresses can be either static or dynamic. Static IP addresses never change. They serve as a permanent Internet address and provide a simple and reliable way for remote computers to contact you. Static IP addresses reveal such information as the continent, country, region, and city in which a computer is located; the ISP (Internet Service Provider) that services that particular computer; and such technical information as the precise latitude and longitude of the country, as well as the locale, of the computer. Many websites provide IP address look-up services to their visitors, free of charge. If you're curious about your own IP address, you can locate these websites by performing a Google search.
Dynamic IP addresses are temporary and are assigned each time a computer accesses the Internet. They are, in effect, borrowed from a pool of IP addresses that are shared among various computers. Since a limited number of static IP addresses are available, many ISPs reserve a portion of their assigned addresses for sharing among their subscribers in this way. This lowers costs and allows them to service far more subscribers than they otherwise could.
Static IP addresses are generally preferable for such uses as VOIP (Voice over Internet Protocol), online gaming, or any other purpose where users need to make it easy for other computers to locate and connect to them. Easy access can also be facilitated when using a dynamic IP address through the use of a dynamic DNS service, which enables other computers to find you even though you may be using a temporary, one-time IP address. This often entails an extra charge, however, so check with your ISP.
Static IP addresses are considered somewhat less secure than dynamic IP addresses, since they are easier to track for data mining purposes. However, following safe Internet practices can help mitigate this potential problem and keep your computer secure no matter what type of IP address you use.
IP Address is Logical Address. It is a Network Layer address (Layer 3)
Two Versions of IP:
IP version 4 is a 32 bit address
IP version 6 is a 128 bit address
IP version 4
Bit is represent by 0 or 1 (i.e. Binary)IP address in binary form (32 bits):
01010101000 00 101 10 11 11 11 00 00 00 01
32 bits are divided into 4 Octets:
01010101. 00000101. 10111111. 00000001
IP address in decimal form:
85.5.191.1
Binary values of an IP address
Binary value of first octect
where,
27 =
128
26 =
64
25 =
32
24 = 16
23 = 8
22 = 4
21 = 2
20 = 1
01010101. 00000101. 10111111. 00000001
the decimal value first octet of this IP is
01010101. 00000101. 10111111. 00000001
ie:
128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 85
the value of first octet is 85
85.00000101. 10111111. 00000001
same way all the other octet works on the same principle
so after converting
01010101. 00000101. 10111111. 00000001
you will get the decimal format like
85.5.191.1
like that if we are taking the first octet
Rolling of IP address will be like as follows
0.0.0.0------------------------------->first IP
0.0.0.1
0.0.0.2
0.0.0.3
0.0.0.4
.
.
.
.
.
.
.
.
0.0.0.0255
0.0.1.0
0.0.1.1
0.0.1.2
0.0.1.3
0.0.1.4
0.0.1.5
0.0.1.6
.
.
.
.
.
.
.
.
.0.0.0.1.255
0.0.2.0
0.0.2.1
0.0.2.2
0.0.2.3
.
.
.
.
.
0.0.2.255.
.
.
.
.
.
.255.255.255.255-------------------------->last IP
so from 0.0.0.0 to 255.255.255 there will be about
4294967296 (232) ip address
And these IP's are clasiffied into 5 calsses
they are
if it begins in between
0 -127 = CLASS A
128 - 190 = CLASS B
191 - 223 = CLASS C
224 - 239 = CLASS D
240 - 255 = CLASS E
eg: 10.0.0.1
Take the first octet of the IP address its 10 so check where it
is coming in the above range ?
Its coming in the first range ,so this is an
A CLASS IP address
lets check another one
192.168.1.1 ?
(its C Class )
what about 129.0.0.3??
its (B Class)
lets try some more
find the Binary format and class of the following IP ADDRESS
192.168.5.1
10.0.0.1
129.0.0.10
160.60.20.1
lets try some more
find the Binary format and class of the following IP ADDRESS
192.168.5.1
10.0.0.1
129.0.0.10
160.60.20.1
IP ADDRESS OCTET FORMAT
HOW DO COMPUTERS COMMUNICATE WITH EACH OTHER
Using a network
connection, including connecting to the Internet, computers connect
to each other to transmit data between them and communicate with
Think of TCP/IP as a book of rules, a
step-by-step guide that each computer uses to know how to talk to another
computer. This book of rules dictates what each computer must do to transmit
data, when to transmit data, how to transmit that data. It also states how to
receive data in the same manner. If the rules are not followed, the computer
will not be able to connect to another computer, nor send and receive data
between other computers.
Internet service providers (ISP), the companies that provide Internet service and connectivity also follow these rules. The ISP provides a bridge between your computer and all the other computers in the world, which are all a part of the Internet. The ISP uses the TCP/IP protocols to make computer-to-computer connections possible and transmit data between them. When successfully connected to an ISP you will be assigned an IP address, which is a unique address given to your computer or network and allows it to be found while on the Internet.
If you have a home computer network, the computers are also using TCP/IP to connect to each other. This protocol allows each computer to "see" the other computers on the network and share files between them and is what makes it possible for a printer to be shared on a network. When computers connect to each other on the same network, it is called a local area network, or LAN. When multiple networks are connected to each other, it is called a wide area network, or WAN.
With this type of network, your
home will have a network router that connects to your ISP. The
router is given the IP address for your connection to the Internet and then
assigns local IP addresses to each device in your network. These local
addresses are often 192.168.1.2-255. When accessing a local computer in your own
network, your router sends your TCP/IP packets between the local IP addresses.
However, when you want to connect to the Internet your router communicates to
the Internet with the IP address assigned to it from the ISP. This is why when
on the Internet your IP address is not a 192.168.x.x address.
When requesting information from a
web page, such as Computer Hope you enter a URLthat is easy to
understand and remember. In order for your computer to access the computer
containing the pages that URL must be converted into an IP address, this is
done with DNS.
Once DNS has converted the URL into an IP address the routers on the Internet
will know how to route your TCP/IP packet. Below is a graphic illustration of
everything explained above to help better illustrate the process of your
computer communicating with another computer on the Internet.
Today, computers using the Microsoft
Windows OS, Apple OS and Linux OS all use the TCP/IP protocol to connect to
other computers on a LAN or WAN. Connecting to a LAN or WAN requires either a
wired connection or a wireless connection. A wired connection is usually done
using a network cable (Cat5 or Cat6 network cable).
A wireless connection (Wi-Fi)
is done using a 802.11b, 802.11g or 802.11n wireless network card. With both
connection types, a network router is usually required to connect to other
computers. Connecting to the Internet at your home will also require either
a cable modem or
a DSL modem,
depending on which ISP you use.
Its simple,consider that computers are communicating
COM 1 COM 2
Here both IP address Starts with 10, and we know that its an A class IP address in the table above its shown that there are one N portion and three H portion ,which mean that the are one network portion and three host potion ,
if the ip address is in A class all the computers in the network has to be assigned the same network portion ..
like here both the IPs start with 10 so it will communicate with each other
Network & Broadcast Address
Terms you need to know:
CIDR: Classless
Inter-Domain Routing. Think of it as a replacement for a Netmask. The CIDR
Value is equivalent to the number of on bits in a 32 bit address going left to
right. For example: the CIDR value of 24 means the first 24 bits are turned on
and the last 8 bits are turned off: 11111111.11111111.11111111.00000000. (See RFC's:
1519, 1817, 4632).
Network address : IP address with all bits as ZERO in the host portion.
Broadcast address : IP address with all bits as ONES in the host
portion.
Valid IP Addresses lie between the Network Address and the
Broadcast Address.
Network Address : 0xxxxxxx.00000 00 0 . 00 000 00 0 . 000 00 00 0
Broadcast Address : 0xxxxxxx.11111 11 1 . 11 111 11 1 . 111 11 11 1
Class B : N.N.H.H
Network Address : 10xxxxxx. x x x x x x x x .00 00 00 00 .00 00 00 00
Broadcast Address : 10xxxxxx. x x x x x x x x .11 11 11 11 .11 11 11 11
Network Address : 110xxxxx. x x x x x x x x . x x x x x x x x .0 00 00 000
Broadcast Address :110xxxxx. x x x x x x x x . x x x x x x x x .1 11 11 111
Example - Class A
Class A : N.H.H.HNetwork Address : 0xxxxxxx.00000 00 0 . 00 000 00 0 . 000 00 00 0
Broadcast Address : 0xxxxxxx.11111 11 1 . 11 111 11 1 . 111 11 11 1
Example - Class B
Class B : N.N.H.H
Network Address : 10xxxxxx. x x x x x x x x .00 00 00 00 .00 00 00 00
Broadcast Address : 10xxxxxx. x x x x x x x x .11 11 11 11 .11 11 11 11
Example - Class C
Class C : N.N.N.HNetwork Address : 110xxxxx. x x x x x x x x . x x x x x x x x .0 00 00 000
Broadcast Address :110xxxxx. x x x x x x x x . x x x x x x x x .1 11 11 111
The
Steps to identify the Network and Broadcast Address of a Sunbelt
Convert the IP Address
and CIDR (or Netmask) to binary. In our lesson entitled Decimal and Binary Conversion
of IP Addresses we gave you the tools to convert any IP to Binary. If you need
additional help you can try our handy IP Conversion Calculators.
Use a Bitwise AND (IP
& CIDR) Operator to return the corresponding values of the IP and CIDR
addresses. This gives you the Network Address (Network ID) A simple way to use
the Bitwise AND Operator in Binary is show in the following example:
IP Address: 192.168.1.15
CIDR: 24 (Netmask:
255.255.255.0)
Binary IP Address:
11000000.10101000.00000001.00001111
Binary CIDR: 11111111.11111111.11111111.00000000
Using the Bitwise AND
(&) Operator, compare the Binary IP Address to the Binary CIDR Address. The
result will be the Network Address of the IP Address we are using:
Binary IP: 11000000.10101000.00000001.00001111
Binary CIDR: 11111111.11111111.11111111.00000000
Binary Network: 11000000.10101000.00000001.00000000
The resultant Network
Address is 11000000.10101000.00000001.00000000. Converting this back to the
format of an IPv4 Address gives us 192.168.1.0. This is our Network Address.
Therefore, 192.168.1.15 belongs to the 192.168.1.0/24 network.
To get the Broadcast
Address we need to do a Binary inversion of the CIDR or Netmask Address.
The inversion of the CIDR
Address of 11111111.11111111.11111111.00000000 becomes:
00000000.00000000.00000000.11111111.
Now we use the Bitwise OR
Operator on the Binary Network Address and the inverted CIDR Address to get the
Broadcast address.
Binary Network Address: 11000000.10101000.00000001.00000000
Inverted Binary CIDR: 00000000.00000000.00000000.11111111
Binary Broadcast Address: 11000000.10101000.00000001.11111111
We now convert
11000000.10101000.00000001.11111111 to IPv4 Decimal octet: 192.168.1.255.
The Broadcast Address for
the 192.168.1.0/24 Subnet is 192.168.1.255.
Now that you have your
feet wet,
let's try a few more.
identify the Network and Broadcast Addresses
for each of the following examples:
1. 10.10.1.97/23
2. 192.168.0.3/25
Example one: Convert 10.10.1.97/23 to Binary.
IP Address: 00001010.00001010.00000001.01100001
CIDR Address: 11111111.11111111.11111110.00000000
Use Bitwise AND Operator (IP & CIDR):
IP Address: 00001010.00001010.00000001.01100001
CIDR Address: 11111111.11111111.11111110.00000000Network Address: 00001010.00001010.00000000.00000000
Binary CIDR: 11111111.11111111.11111110.00000000
Inverted Binary CIDR: 00000000.00000000.00000001.11111111
IP: 11000000.10101000.00000000.00000011
CIDR: 11111111.11111111.11111111.10000000
Network: 11000000.10101000.00000000.00000000
Binary CIDR: 11111111.11111111.11111111.10000000
Inverted Binary CIDR: 00000000.00000000.00000000.01111111
Network Address: 10.10.0.0
Binary Inversion of CIDR:
Use Bitwise OR Operator to get the Broadcast Address:
Binary Network: 00001010.00001010.00000000.00000000
Inverted Binary CIDR: 00000000.00000000.00000001.11111111
Binary Broadcast: 00001010.00001010.00000001.11111111
Broadcast Address: 10.10.1.255
IP Address 10.10.1.97/23 belongs to the 10.10.0.0/23 Network.
The network
Address is 10.10.0.0 and the Broadcast Address is 10.10.1.255.
Example two: Convert
192.168.0.3/25 to Binary.
IP Address: 11000000.10101000.00000000.00000011
CIDR Address: 11111111.11111111.11111111.10000000
Use Bitwise AND Operator (IP & CIDR):
Network Address: 192.168.0.0
Binary Inversion of CIDR:
Use Bitwise OR Operator to get the Broadcast Address:
Binary Network: 11000000.10101000.00000000.00000000
Inverted Binary CIDR: 00000000.00000000.00000000.01111111
Binary Broadcast: 11000000.10101000.00000000.01111111
Broadcast Address: 192.168.0.127
IP Address 192.168.0.3/25 belongs to the 192.168.0.0/25 Network.
The network
Address is 192.168.0.0 and the Broadcast Address is 192.168.0.127.
Private IP Address
When you send a letter
from your house to a friend, you have to know the address to send it to so that
the postman knows which street and which house to take it to. Computer networks
such as the Internet are no different except instead of sending your web
traffic to "1145 Main Street"; your computer's location is known as
an IP Address.
An IP address is
your computer's equivalent of your postal address and just like the mail
service, each computer has to have its own address so that it will only receive
the information that is meant for it and not anything that is meant for someone
else.
While we are used
to writing out streets and house numbers on envelopes, inside your computer IP
Addresses are usually represented in what is known as dotted-decimal format
such as 124.62.112.7 as this is the system that is understood by computers. As
you can see, the address is split into 4 sections known as "octets"
and each of the four octets can be numbered from 0-255, providing a total of
4,294,967,296 potentially unique IP Addresses.
Now, while 4.2
Billion might seem like a lot, for many years large amounts of these have been
allocated and used by large network such as backbone providers, ISPs and large
Universities that made up the early Internet While other groups still have been
reserved for special purposes and are not usable, so in practice the real
amount is far less than 4.2 billion. The problem that we face today is that
with many homes owning more than one computer and with cell phones, PDAs and
even fridges being enabled for Internet access these days, IP Addresses are
running out.
When I mentioned
above that some blocks of addresses had been reserved for special purposes, one
of these purposes was for private networking and it is these private addresses
that help to relieve the pressure on the remaining address space and make
possible many of the cable and DSL routers that people have at home today to
share their Internet connection amongst many PCs.
Private IP address ranges
The ranges and the
amount of usable IP's are as follows:
10.0.0.0 -
10.255.255.255
Addresses: 16,777,216
Addresses: 16,777,216
172.16.0.0 -
172.31.255.255
Addresses: 1,048,576
Addresses: 1,048,576
192.168.0.0 -
192.168.255.255
Addresses: 65,536
Addresses: 65,536
So, what are these addresses and how do they work?
For example, if I
had 6 computers that I wanted to network, I might number them from 172.16.0.1
up to 172.16.0.6 and this would still leave over a million more addresses that
I could use if I were to buy some more computers or if I was networking a large
office and needed lots and lots of addresses.
These blocks of
addresses can be used by anyone, anywhere - even if your neighbor is using the
exact same addresses this won't cause a problem. This is possible because these
addresses are known as "non-Routable addresses" and the devices on
the internet that move data from one place to another are specially programmed
to recognize these addresses. These devices (known as routers) will recognize
that these are private addresses belonging to your network and will never
forward your traffic onto the Internet so for your connection to work; you will
always require at least one real address from the general pool so that your
home router can perform what is known as "Network Address Translation".
NAT is a process
where your router changes your private IP Address into a public one so that it
can send your traffic over the Internet, keeping track of the changes in the
process. When the information comes back to your router, it reverses the change
back from a real IP Address into a private one and forwards the traffic back to
your computer.
Private addresses
and NAT is what makes your home router work and by using them, anyone is able
to connect as many computer's as they wish to the Internet without having to
worry about running out of addresses and this gives everyone many more years
until all the available addresses are used up
There are certain addresses in each class of IP address that are
reserved for Private Networks. These addresses are called private
addresses.
These addresses are not Routable (or) valid on Internet.
Subnet mask
A subnet allows the flow of network traffic
between hosts to be segregated based on a
network configuration. By organizing
hosts into logical groups, subnetting can improve
network security and
performance.
Subnet Mask
Perhaps the most recognizable aspect of subnetting is the subnet mask. Like IP addresses,
a subnet mask contains four bytes (32 bits) and is often written using the same
"dotted-decimal" notation. For example, a very common subnet mask in
its binary representation
11111111
11111111 11111111 00000000
is typically shown in the
equivalent, more readable form
255.255.255.0
Applying a Subnet Mask
A subnet mask neither works like an IP address, nor does it
exist independently from them. Instead, subnet masks accompany an IP address
and the two values work together. Applying the subnet mask to an IP address
splits the address into two parts, an "extended network address" and
a host address.
For a subnet
mask to be valid, its leftmost bits must be set to '1'. For example,
00000000
00000000 00000000 00000000
is an invalid subnet mask because
the leftmost bit is set to '0'.
Conversely,
the rightmost bits in a valid subnet mask must be set to '0', not '1'.
Therefore,
11111111
11111111 11111111 11111111
is invalid.
All valid
subnet masks contain two parts: the left side with all mask bits set to '1'
(the extended network portion) and the right side with all bits set to '0' (the
host portion), such as the first example above.
Subnetting
in Practice
Subnetting
works by applying the concept of extended
network addresses to
individual computer (and other network device) addresses.
An extended network address includes both a network address and additional bits that represent the subnet number... (see below) |
||||||||||||||||||||||||||
... .
Together, these two data elements support a two-level addressing scheme
recognized by standard implementations of IP. The network address and subnet
number, when combined with thehost address, therefore support a
three-level scheme.
Consider the following real-world example. A small business
plans to use the 192.168.1.0 network for its internal (intranet) hosts. The human resources
department wants their computers to be on a restricted part of this network
because they store payroll information and other sensitive employee data. But
because this is a Class C network, the default subnet mask of255.255.255.0 allows all computers
on the network to be peers (to send messages directly to each other) by
default.
The first
four bits of 192.168.1.0 -
1100
place this
network in the Class C range and also fix the length of the network address
at 24 bits. To subnet this network, more than 24 bits must be set to '1' on
the left side of the subnet mask. For instance, the 25-bit mask 255.255.255.128 creates a two-subnet network as follows.
For every additional bit set to '1' in the mask, another bit
becomes available in the subnet number to index additional subnets. A two-bit
subnet number can support up to four subnets, a three-bit number supports up
to eight subnets, and so on.
Private Networks and Subnets
As
mentioned earlier in this tutorial, the governing bodies that administer
Internet Protocol have reserved certain networks for internal uses. In
general, intranets utilizing these networks gain more control over managing
their IP configuration and Internet access. The default subnet masks
associated with these private networks are listed below.
Consult RFC 1918 for more details about these special networks.
Subnetting Review
Subnetting
allows network administrators some flexibility in defining relationships
among network hosts. Hosts on different subnets can only "talk" to
each other through specialized network gateway devices like routers. The ability to filter traffic
between subnets can make more bandwidth available to applications and can
limit access in desirable ways.
|
Class
|
Address
|
# of Hosts
|
Netmask (Binary)
|
Netmask (Decimal)
|
CIDR
|
/4
|
240,435,456
|
11110000 00000000
00000000 00000000
|
240.0.0.0
|
CIDR
|
/5
|
134,217,728
|
11111000 00000000
00000000 00000000
|
248.0.0.0
|
CIDR
|
/6
|
67,108,864
|
11111100 00000000
00000000 00000000
|
252.0.0.0
|
CIDR
|
/7
|
33,554,432
|
11111110 00000000
00000000 00000000
|
254.0.0.0
|
A
|
/8
|
16,777,216
|
11111111 00000000
00000000 00000000
|
255.0.0.0
|
CIDR
|
/9
|
8,388,608
|
11111111 10000000
00000000 00000000
|
255.128.0.0
|
CIDR
|
/10
|
4,194,304
|
11111111 11000000
00000000 00000000
|
255.192.0.0
|
CIDR
|
/11
|
2,097,152
|
11111111 11100000
00000000 00000000
|
255.224.0.0
|
CIDR
|
/12
|
1,048,576
|
11111111 11110000
00000000 00000000
|
255.240.0.0
|
CIDR
|
/13
|
524,288
|
11111111 11111000
00000000 00000000
|
255.248.0.0
|
CIDR
|
/14
|
262,144
|
11111111 11111100
00000000 00000000
|
255.252.0.0
|
CIDR
|
/15
|
131,072
|
11111111 11111110
00000000 00000000
|
255.254.0.0
|
B
|
/16
|
65,534
|
11111111 11111111
00000000 00000000
|
255.255.0.0
|
CIDR
|
/17
|
32,768
|
11111111 11111111
10000000 00000000
|
255.255.128.0
|
CIDR
|
/18
|
16,384
|
11111111 11111111
11000000 00000000
|
255.255.192.0
|
CIDR
|
/19
|
8,192
|
11111111 11111111
11100000 00000000
|
255.255.224.0
|
CIDR
|
/20
|
4,096
|
11111111 11111111
11110000 00000000
|
255.255.240.0
|
CIDR
|
/21
|
2,048
|
11111111 11111111
11111000 00000000
|
255.255.248.0
|
CIDR
|
/22
|
1,024
|
11111111 11111111
11111100 00000000
|
255.255.252.0
|
CIDR
|
/23
|
512
|
11111111 11111111
11111110 00000000
|
255.255.254.0
|
C
|
/24
|
256
|
11111111 11111111
11111111 00000000
|
255.255.255.0
|
CIDR
|
/25
|
128
|
11111111 11111111
11111111 10000000
|
255.255.255.128
|
CIDR
|
/26
|
64
|
11111111 11111111
11111111 11000000
|
255.255.255.192
|
CIDR
|
/27
|
32
|
11111111 11111111
11111111 11100000
|
255.255.255.224
|
CIDR
|
/28
|
16
|
11111111 11111111
11111111 11110000
|
255.255.255.240
|
CIDR
|
/29
|
8
|
11111111 11111111
11111111 11111000
|
255.255.255.248
|
CIDR
|
/30
|
4
|
11111111 11111111
11111111 11111100
|
255.255.255.252
|
SubnetMask - Examples
Class A : N.H.H.H
11111111.00000000.00000000.00000000
Default Subnet Mask for Class A is 255.0.0.0
Class B : N.N.H.H
11111111.11111111.00000000.00000000
Default SubnetMask for Class B is 255.255.0.0
Class C : N.N.N.H
11111111.11111111.11111111.00000000
Default SubnetMask for Class C is 255.255.255.0
How Subnet MaskWorks ?
IP Address : 192.168.1.1
SubnetMask : 255.255.255.0
ANDING PROCESS :
192.168.1.1 = 11000000.10101000.00000001.00000001
255.255.255.0 = 11111111.11111111.11111111.00000000
==================================================
192.168.1.0 = 11000000.10101000.00000001.00000000
==================================================
The output of an AND table is 1 if both its inputs are 1.
For all other possible inputs the output is 0.
