What is an IP Address?

This tutorial covers everything one like to know about networking basics including circuit switching vs packet switching, TCP/IP protocol fields, ARP/RARP protocol fields, what is IP address ,what is MAC address, networking devices which include hub, switch, bridge, router, gateway and firewall.

This page describes internet protocol address,its classes,telephone analogy and commands. It is a short form of Internet Protocol Address.This is very important address which is used by any device(desktp,laptop,tablet,mobile,ipad) to connect to the internet. To learn about what an ip address is, let us compare with telephone system analogy.
The way telephone number is required to connect with circuit switched telephone network by any mobile/landline wanting to utilize voice service. Similarly IP address is required by the device wanting to connect to packet switched network to obtain data service. IP Address are of two types IPV4 and IPV6.
IPV4 is in use throughout the world and IPV6 is under trial.IP address is the part of TCP/IP Protocol Suit and is very important to know.

Unlike telephone number which has been assigned by telephone company or mobile service provider. IP address can be assigned to the device by internet service provider.
There are two ways device can be assigned this IP address. one way is static or manual configuration and the other way is dynamically it is assogned to the device by server. server is located at the internet service provider's premise with which device will connect to obtain internet service. DHCP protocol assigns this dynamic IP address to the device requesting for internet data connection.

IPV4 address is a 32 bit number. IP addresses are usually written in what is called dotted decimal notation,with a decimal number representing each of the octets of the 32-bit address. For example, the IP address 11000000 11100100 00010001 00111001 is written as
There are four main classes. Class A,Class B,Class C and Class D.
Class A- 0, network(7 bits), host (24 bits)
Class B- 10, network(14 bits), host (16 bits)
Class C- 110, network(21 bits), host (8 bits)
Class D- 1110, rest of the bits are for multicast
Class E-11110,rest of the bits are for future us
For Class C, host id space is 8 bits long, 2 to the power 8 is 256 hence 256 hosts i.e. computers are supported in class C. Hence appropriate class is selected based on need of networks and hosts. Remember initial decimal digit i.e. first 8 bits to differentiate between these four classes i.e. network ID. For class A, network ID is from 0 to 127
For class B, network ID is from 128 to 191
For class C, network ID is from 192 to 223
For class D, network ID is from 224 to 239
For class E, network ID is from 240 to 255

For special purposes, some IP addresses are reserved similar to some telephone numbers reserved for emergency and special purposes. is the self loop back IP address to check the system's Ethernet card is working or not. This is useful when you do not know the IP address configured for the card. i.e. FF:FF:FF:FF is reserved for broadcast purposes. For more information please visit the link mentioned in RELATED LINKS below.
IPV6 includes 128 bit source and destination address fields. Ultimately, all installations using TCP/IP are expected to migrate from the current IPV4 to IPV6, but this process will take time.

Commands to know IP address

In windows machine: ipconfig
Click Programs
Click Accessories
Click Command prompt
Type ipconfig/all
Will list out IP address as well as MAC or physical address of the Ethernet card or chip embedded in the device.
Following diagram lists ip address of the system where "ipconfig/all" command is issued. In UNIX machine: ifconfig

Commands to know whether system is connected to IP network or is reachable to particular server or network through wired or wireless medium.

ping destination_ipaddress
For Example, ping
What ping does is,
it sends some known bytes to the destination computer with which source computer wants to check ip connectivity. The destination computer replies the same bytes back, which source computer or device compares with originalal bytes sent and will determine if all the bytes received back correctly or not and will hence determine the status of connection.
This is the reason IP address has become popular for the device not only to utilize internet service but also used for remote controlling of the device or for automation.


RFC 791- Internet Protocol-DARPA,available for download from ietf.org
RFC 3330- For Special Use of IPv4 Addresses,available for download from ietf.org
RFC 2460 - Internet Protocol, Version 6 (IPv6)Specification, available for download from ietf.org
RFC 1918- Address Allocation for Private Internets.
IANA IPv4 Address Space Registry, iana.org
IANA-IANA is responsible for global coordination of the Internet Protocol addressing systems, as well as the Autonomous System Numbers used for routing Internet traffic.

This page explains what an ip address is, gives various classes,commands and useful references.

What is?

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Networking related links

Circuit Switching vs Packet switching   LAN vs WAN vs MAN   What is an IP address   What is MAC Address   Basics of OSI and TCP-IP Layers   What is Hub   What is Switch   What is Bridge   What is Router   What is Gateway   Firewall basics   TCP-IP Packet format   ARP Protocol format  

RF and Wireless Terminologies