# Understanding TCP/IP basics

IP is a logical address by combining four numbers. We can find IP addresses in different numbers like below:

192.168.1.1

172.16.1.1

10.10.10.1

And so many more IPs we may get.

Now, to understand these numbers we need to know about few terms here.

1. Bit
2. Byte
3. Octet

#### Bit:

Bit is a one digit number which is either 1 or 0. In case of network it’s just number but in other electronics it may represent on or off.

#### Byte:

Byte is a combination of 1 and 0. A combination or 8 digits 1 or 0 is a byte. It seems like below:

10011011

Using decimal conversion we can also represent it in a decimal number. In this case the decimal is 139.

#### Octet:

In case of IP address we have four parts, each part is called octet. Because each part of IP address is a combination of 8 bits. So we can say that a combination of 8 bits is an octet.

This was done during the first introduction of IP addressing. It was presented so that different organizations can accommodate different size of network and keep them organized. If we follow this classification than we usually call that classfull addressing.

We can find three classfull addressing which are being used in organizations.

Class A: class A IPs classified by the first octet of the IP address. The first octet will be within 1-126 and the octet will be 00000001 to 01111110. Its first octet is the network part and the rest is network part.

Class B: in case of Class B IPs the first octet will be within 127-191 and the octet will be 10000000 to 10111111. Its first two octets are network parts and last two octets are host part.

Class C: class C IPs start from 192 and ends at 223. The octets are 11000000 to 11011111. Its first three octets are network part and the last part is host part.

Usually the first address of an IP series is the network address of that network. It depends on the prefix we put on an IP address. We can see that almost every IP address is given that have a number at the end of the address which is represented by /.  Suppose we designed a network series which is 192.168.1.0/24, so here the network address is 192.168.1.0. But we have a prefix of 29. Suppose another IP address is 192.168.1.24/29. So here the network address is 192.168.1.24.

The address that is used to send information to the next node is known as broadcast address. Usually the last IP address of a network is known as broadcast address. This address is usually used to introduce itself to the neighbor networks.

1. It is a 32 bit dotted decimal number with 4 octets, each octet of 8 bits.
2. It is divided into two portions, network and host portion.
3. IP addresses must be unique in a network.
4. Each octet has a decimal value range of 0 to 255.
5. The first cannot be 127, this is reserved for loopback.
6. All 0 octets mean all networks in the world.

Every single point brought here has an elaborated and detailed description and I hope I would describe all those issues in next articles. But for now I believe this brief summary can give us a simple concept about TCP/IP model.

1 Comment
1. NewkidaaBlog says

Nice post

Thanks for sharing