Network Testing: Core Networking (Foundation) part 1

Hi, I am starting a Network testing blog writeups series from basic. So, Let’s get started

credit: centraleyes.com

Topics:

• OSI model
• TCP/IP model
• Gateway and IP

OSI model: The Open Systems Interconnection (OSI) model is a 1984 conceptual framework standardized by the ISO that breaks network communication into seven distinct layers. Well, this doesn’t work in real life

Layers are:

• Application layer: This layer directly interacts with websites such as HTTP/HTTPS, SMTP.
• Presentation Layer: This layer help in encryption of data such as SSL/TLS.
• Session Layer: This layer responsible for sessions between 2 devices such as session cookies.
• Transport Layer: This layer is responsible for flow of data for example (TCP/UDP).
• Network Layer: This layer is responsible for data routing across multiple networks.
• Data link Layer: This layer is to make sure the data transfer to physical layer must be error-free and properly framed.
• Physical Layer: This is lowest layer of the OSI model it operates and make data available from data link layer to hardware in a binary format. This includes data transfer from cables and switches

TCP/IP model:

The TCP/IP model is a four-layered, standardized framework. That defines how data is packetized, addressed, transmitted, routed, and received over networks. This one use in real life

In this as you know there are only 4 layers which are:

• Application layer: This layer directly interacts with websites such as HTTP/HTTPS, SMTP.
• Transport layer: This layer is responsible for flow of data for example (TCP/UDP).
• Internet layer: This layer is responsible for routing data from devices to other devices in a subnet.
• Network access layer: This layer is responsible for data routing across multiple networks. such as MAC, Ethernet.

credit: tecadmin.com

• IP: IP(internet protocol) it is unique 32 bits address assign to a particular device this is made of 32 bits such (4 Octet) for example

00000000.00000000.00000000.00000000 --> 0.0.0.0 
11111111.11111111.11111111.11111111 --> 255.255.255.255

• This address is made to interact with internet and other devices.
• Gateway: Gateway is device use to connect a particular organization with whole world internet so the organization can use the internet too.

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