IP Address is a unique identification given to Host, network
device, server for data communication. IP Address stand for Internet Protocol address, it is an addressing
scheme used to identify a system on a network. It is a unique address that
certain electronic devices currently use to communicate with each other on a
network using internet protocol.
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| IPv4 & IPv6 Header Difference |
IP Version 4
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| IPv4 Address |
IP Version 6
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| IPv6 Address |
Since IPV6 provides us with more number of addresses when
compared to IPV4 i.e., IPV6 supports 2128(about 3.4×1038) addresses, or
approximately 5×1028 addresses for each of the 6.5 billion people alive today.
IPv4 Classes
IP Addresses can be classified into five classes A, B, C, D
and E. Each class consists of a contiguous subset of the overall IPv4 address
range.
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| Available Network & Host Bit in IP Classes |
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| IP Range in Different Classes |
Class A
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| IP Address Class A |
The network ID is not allowed to have all its bits set to 0
or all bits set to 1. The 127 network ID is excluded from this address class.
Thus, 126 possible Class A networks are available to organizations around the world. With only 126 Class A networks, owning one puts you in an exclusive club. You can no longer acquire a network block of addresses, and when possible, IANA gets them back from the registered owners. Getting addresses back allows IANA to redistribute addresses in a more efficient and temporary manner.
Class B
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| IP Address Class B |
The definition of the Class B network is represented with a
subnet mask, but the Class B network ID is made up of the values in the first
two octets. Unlike Class A networks, all network IDs in this range are available
for use.
Class C
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| IP Address Class C |
The default subnet mask for Class C networks defines the first three octets as the network ID for these networks. Like with Class B networks, all the network IDs are available for use on networks. This is the last of the network classes that will be used for network devices on a TCP/IP network.
Class D
Class D network addresses are not assigned to devices on a
network. These addresses are used for special-purpose, multicast applications
(such as video and audio-streaming applications).
These addresses all need to be registered with IANA to be used globally. Addresses in this class have the first bits of the first octet set to 1110, yielding addresses in the first octet ranging from 11100000 to 11101111, or 224 to 239. These addresses are not defined by a normal subnet mask; instead, each address is used for a specific purpose. And because each address is individually used, it uses a 255.255.255.255 mask.
Class E
If Class D is special, Class E addresses are even more
special. There is no defined use for this address class. Officially, it is
listed as reserved for usage and testing by IANA and the Internet Research Task
Force (IRTF). In fact, as of RFC3330 in 2002, Class E was updated to “reserved
for future use.”
Class E comprises absolutely all valid addresses with 240 or higher in the first octet. The first bits of the first octet is 1111, which yields addresses from 11110000 to 11111110 — or technically, 11111111 — which, in decimals, are 240 to 254 — or 255.
Because this address class is not being used for address allocation,
you cannot know what the network ID, which defines the valid addresses in a
range. So the inclusion of 255 at the end of the range is moot because this
address range is not available for you to use. All you need to know is that by
definition Class E includes all valid addresses higher than Class D.
IP Addressing
There are four forms of IP addressing, each with its own
unique properties.
- Unicast: The most common concept of an IP address is in unicast addressing, available in both IPv4 and IPv6. It normally refers to a single sender or a single receiver, and can be used for both sending and receiving. Usually, a unicast address is associated with a single device or host, but it is not a one-to-one correspondence. Some individual PCs have several distinct unicast addresses, each for its own distinct purpose. Sending the same data to multiple unicast addresses requires the sender to send all the data many times over, once for each recipient.
- Broadcast: In IPv4 it is possible to send data to all possible destinations ("all-hosts broadcast"), which permits the sender to send the data only once, and all receivers receive a copy of it. In the IPv4 protocol, the address 255.255.255.255 is used for local broadcast. In addition, a directed (limited) broadcast can be made by combining the network prefix with a host suffix composed entirely of binary 1s. For example, the destination address used for a directed broadcast to devices on the 192.0.2.0/24 network is 192.0.2.255. IPv6 does not implement broadcast addressing and replaces it with multicast to the specially-defined all-nodes multicast address.
- Multicast: A multicast address is associated with a group of interested receivers. In IPv4, addresses 224.0.0.0 through 239.255.255.255 (the former Class D addresses) are designated as multicast addresses. IPv6 uses the address block with the prefix ff00::/8 for multicast applications. In either case, the sender sends a single datagram from its unicast address to the multicast group address and the intermediary routers take care of making copies and sending them to all receivers that have joined the corresponding multicast group.
- Anycast: Like broadcast and multicast, anycast is a one-to-many routing topology. However, the data stream is not transmitted to all receivers, just the one which the router decides is logically closest in the network. Anycast address is an inherent feature of only IPv6. In IPv4, anycast addressing implementations typically operate using the shortest-path metric of BGP routing and do not take into account congestion or other attributes of the path. Anycast methods are useful for global load balancing and are commonly used in distributed DNS systems.
Automatically Assigned Addresses
There are several IP addresses that are automatically
assigned when you setup a home network. These default addresses are what allow
your computer and other network devices to communicate and broadcast
information over your network. Below is the most commonly assigned network
addresses in a home network.
192.168.1.0
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0 is the
automatically assigned network address.
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192.168.1.1
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1 is the commonly
used address used as the gateway.
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192.168.1.2
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2 is also a
commonly used address used for a gateway.
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192.168.1.3 - 254
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Addresses beyond 3
are assigned to computers and devices on the network.
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192.168.1.255
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255 is
automatically assigned on most networks as the broadcast address.
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If you have ever connected to your home network, you should
be familiar with the gateway address or 192.168.1.1, which is the address you
use to connect to your home network router and change its settings.
Getting an IP Address
By default the router you use will assign each of your
computers their own IP address, often using NAT to forward the data coming from
those computers to outside networks such as the Internet. If you need to
register an IP address that can be seen on the Internet, you must register
through InterNIC or use a web host that can assign you addresses.
Anyone who connects to the Internet is assigned an IP address
by their Internet Service Provider (ISP) who has registered a range of IP
addresses.
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| Process for getting IP |
Modifications to IP Addressing
- IP blocking and firewalls
Firewalls perform Internet Protocol blocking to protect
networks from unauthorized access. They are common on today's Internet. They
control access to networks based on the IP address of a client computer.
Whether using a blacklist or a whitelist, the IP address that is blocked is the
perceived IP address of the client, meaning that if the client is using a proxy
server or network address translation, blocking one IP address may block many
individual computers.
- IP address translation
Multiple client devices can appear to share IP addresses:
either because they are part of a shared hosting web server environment or
because an IPv4 network address translator (NAT) or proxy server acts as an
intermediary agent on behalf of its customers, in which case the real
originating IP addresses might be hidden from the server receiving a request. A
common practice is to have a NAT hide a large number of IP addresses in a
private network. Only the "outside" interface(s) of the NAT need to
have Internet-routable addresses.
Most commonly, the NAT device maps TCP or UDP port numbers on
the side of the larger, public network to individual private addresses on the
masqueraded network.
In small home networks, NAT functions are usually implemented
in a residential gateway device, typically one marketed as a
"router". In this scenario, the computers connected to the router
would have private IP addresses and the router would have a public address to
communicate on the Internet. This type of router allows several computers to
share one public IP address.
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