How to Answer: Can you describe the OSI reference model, its layers, and their purpose?
Advice and answer examples written specifically for a Network Engineer job interview.
22. Can you describe the OSI reference model, its layers, and their purpose?
How to Answer
As the interview progresses, the technical questions will become more complex and difficult. This indicates that the interviewer is gaining confidence in your capabilities and is willing to challenge you more. Therefore, continue to respond to technical questions directly and succinctly and anticipate follow-up questions from the interviewer.
Answer Example
"OSI stands for Open System Interconnection. It is a reference model that defines how applications communicate with each other over a network. There are seven layers in the model, and each has a specific function. These are:
Physical - How data is transmitted and received through a network medium. Ethernet is an example of this.
Data Link - Defines the error-free transfer of data between network nodes using encoding and decoding.
Network - This layer chooses the physical path that should be taken by the data based on how the network is performing.
Transport - Keeps the messages in sequence, without any loss or replication, resending the data if necessary.
Session - Establishes a session or connection between the processes used by each node, then terminates it.
Presentation - Also known as the syntax layer, formats the data and presents it to the application layer.
Application - Mediates between the users and the applications, providing services such as email and file access."
Anonymous Interview Answers with Professional Feedback
Anonymous Answer
Layer 7 - Application Layer - HTTP, HTTPS
Layer 6 - Presentation Layer
Layer 5 - Session
Layer 4 - Transport (TCP, UDP)
Layer 3 - Network (IP, ICMP)
Layer 2 - Data Link (MAC Address, Frame Relay)
Layer 1 - Physical (Binary, 1s, and 0s)
The primary purpose of the OSI reference model is to help visualize and utilize the reference model during troubleshooting and to know at what layer the issue or problem may be at up and down the OSI stack."
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