OSI Model (Networking)


The modern internet is not based on OSI, but on the simpler TCP/IP model. however, the OSI 7-layer model is still widely used, as it helps visualize and communicate how networks operate and help isolate and troubleshoot networking problems. The OSI model is a reference model for how applications can communicate over networks.

1. APPLICATION (layer 7):

2. PRESENTATION(layer 6):

3. Session (layer 5):

4. Transport(layer4):

5. NETWORK (layer 3 ):

6. Data Link(layer 2):

7. Physical (layer 1 ):



Determine the required hardware and software to build their network.

Understand and communicate the process followed by the components communicating across a network.

Perform troubleshooting by identifying which network layer is causing an issue and focusing efforts on that layer.

Why we need to look at OSI Model:

suppose we need to use Nmap, to understand Nmap we need to understand the flow of the packets and how they are sent. NMAP uses the network layer and the transport layer.