IP Address Basics

Ever wondered, how a computer manages to find another computer in a network?Well there are many ways but the core of finding each other are by the way of unique addresses. Just like we humans find each other by name, computers too have a name. This name is called an ‘IP Address’.  Another name that is very important is a ‘MAC Address’ which we will speak about later.

IP Addresses are numbers that gives presence to a computing device (Laptop, PC, server, mobiles etc) in a network. Computers in a network identify each other by their IP addresses.

To start off  IP addressing follows some standards and there are versions to the standards. The most used version is IPv4. Currently the world is headed towards IPv6 but, Let’s keep ourselves around IPv4 at the moment as IPv4 is to stay almost forever. I don’t think IPv4 will be completely replaced due to the sheer volume of devices on IPv4. There is just too much replacement to do.

IP addressing is like playing guitar. Not very difficult to understand but difficult to master or be even good at. Needless to say, it requires practice to use IP addressing and its concepts in the practical world. However, that’s for another discussion.

Some properties of an IP address:-

  • IP stands for Internet Protocol and represents the protocol that the internet/ networked devices use to find each other.
  • Is a 32 bit address ( 128 bit in IPv6 ) and is made up of 4 octets (32 bits divided into 4 octets of 8 bits each). This is best visualized in a binary notation:
    11000000:10101000:00001010:00001010 
    Octet1 : Octet2 : Octet3 : Octet4

8 bits (an octet) make up a Byte. Alternatively, an IP address is of 4 bytes.

Well, calm down champ.. getting to that in a moment.

Bits or binary digits are the smallest fraction of a message. Well, let’s face it, computers do not understand English or vocabulary in the general sense. Computers understand only binary i.e ‘0’ and ‘1’. Hence, everything you type in English, is being converted to binary by the computer.

A bit consists of a ‘0’ and ‘1’ and hence the name binary digit or bit for short. 8 bits make a byte. 1024 bytes is a kilobyte. 1024*1024 makes a megabyte and so on..

  • An IP Address can be denoted in 3 forms:-

Dotted Decimal:- 192.168.10.10
Binary:-  11000000:10101000:00001010:00001010
Hexadecimal:- 0xC0:A8:0A:0A

  • IP addresses are divided into class ranges A,B,C,D & E. The first octet denotes the class.
    Class Range
    A 1-126 (127 is a loop back address. Should not be used)
    B 128 – 191
    C 192 – 223
    D 224 – 239 (Used for multicast communication)
    E 240 – 255 (Used for experiment/ research)

Hence, IP address 192.168.10.10 belongs to class C. 172.168.10.1 belongs to class B and so on.

As mentioned, a byte or octet is made up of 8 bits (bits is short for binary digits). Every bit in this byte has a ‘place value’ or ‘block size’. A bit can be turned ‘on’ or ‘off’ represented as ‘1’ and ‘0’ respectively.

Considering every bit to be on, the values are as under:

1 1 1 1 1 1 1 1
128 64 32 16 8 4 2 1

If all the bits were ‘on’, then the total value will be 255

if all the bits were ‘off’, then the total value will be 0

Simply put, 0-255 represents a range of IP addresses that can exist. In other words, an IP address can be have in every octet a minimum of 0 and a maximum of 255 represented as 0-255:0-255:0-255:0-255.

To make this sink in further, an IP address can be anywhere in the range of 0.0.0.0 to 255.255.255.255. However, before you shoot the gun, let me tell you that 0.0.0.0 represents all IPs on the local machine and 255.255.255.255 is the broadcast address. Both these addresses are not used in addressing devices. More on these 2 addresses on a different blog.

It will be a big mistake to think that all can be explained in an article. I will not do that mistake, though I will tell you that this is it for starters. You will dig deeper about IP addresses in subnets, masks, CIDR etc because that’s where practicals of IP addressing starts. See you soon with more on IP addressing…

Try the following to get a good grip:-

  • Convert the following into dotted decimal Notation:-

11110000:11001000:11111111:00001000
10101000:00001111:1110000:00011100
11000000:10100000:00110001:11111111

  • Convert the following to binary:-

192.168.10.1
12.132.112.10
172.168.10.32

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