If you ever used internet connection, then you have heard the term IP Address. It is a very popular protocol of both TCP/IP and OSI model. In this article we will know about the basic terminologies related to IP Address.
First, what is IP Address? IP Address is a unique address for every devices connected to network. Think of your home address. If someone wants to send you a gift, he or she have to know your home address. If your home address matches with others, then there is a chance that, you will not receive the gift. Similarly, two network devices can not have same address to work properly. IP Address is that unique address which is responsible for successful delivery of data.
IP Address Structure
Now-a-days, there are two versions available of IP Addressing scheme. IPv4 and IPv6. We will discuss about both of them, briefly.
IPv4: IPv4 has 32 bits. These 32 bits are divided into four octets. Each octet is 8 bits long. For human readability, IP Address are usually presented in decimal number. Each 8 bit binary octet is converted into decimal number. An example of ip address is 192.168.1.100. It has four parts. Value of each part can be from 0 to 255. If you are familiar with binary to decimal conversion, then you will understand from where 255 comes.
IPv6: IPv6 is 128 bits long, which is huge. These 128 bits are expressed in Hexadecimal number system. Usually these addresses are grouped in 8 groups, 16 bits in each group. An example of IPv6 address is, 2001:0db8:0000:0000:0000:ff00:0042:8329.
If IP Address is your home address, then subnet mask defines your neighborhood. IP Address alone is less useful. There are two parts of any ip address. They are network part and host part. Subnet mask distinguish these two parts. Subnet mask has sequence of 1’s starting from left side. This is a continuous sequence. After one O(zero) all remaining bits have to be zero. In binary form a 32 bit subnet mask may look like this. 11111111.11111111.11111111.00000000. If you convert this into decimal, then it will become 255.255.255.0.
Now if this is the subnet mask of 192.168.1.100, that means, first three octet of this address is network part, as there are 24 consecutive 1’s in subnet mask. Rest of the address is host part.
Just like address of a network device, every network is identified of its address. This address is called network address. Network address is the first address of an address range. For example, lets consider an IP address and subnet mask pair is, 192.168.1.128 and 255.255.255.0. As here first three octets are sequence of 1’s then network portion of this address is first three octet. So, first address of this range is 192.168.1.0. This is the network address for all the devices connected in this network.
Lets assume you have a network with 200 devices connected. Now if you want to send a message to everyone of your network, then you have to send it 200 times. This is very time consuming and tiresome work. To avoid this, you can use broadcast address. If you send a message to broadcast address, it will send that message to every device connected into that network. Broadcast address is the last address of a network. From previous example. 192.168.1.255 is the last address.
In computer networking world, people don’t only exchange information only in their own network. Most of the time users send data from one network to another. Default gateway is the address which provide direction to outside network from your local network. Default gateway can be any address of network address range. Its is defined by network administrator.
ARP stands for Address Resolution Protocol. Actually it retrieves the physical addresses of devices. First, a broadcast message is sent to every device. Further, the devices reply with there logical address and physical address. Thus IP Address of every device is mapped against respective devices physical or MAC address.
On the subject of IP Addressing, these are the few important topics. Furthermore, there are other advanced concept you should know about IP Addressing. For those, search in CCNA category of this website. Have a nice day!