OSI Model Test and Flashcards

How many layers are in the OSI model?

7

Physical Layer 1

Handles the physical transmission of data bits over a physical medium (cables, fibers)

Data Link Layer 2

Ensures error-free transmission between network devices using MAC addresses and frames

Network Layer 3

Routes packets across networks based on logical addresses (IP addresses)

Transport Layer 4

Provides reliable data transfer between applications using ports and segments/datagrams

Session Layer 5

Establishes, manages, and terminates sessions between communicating applications

Presentation Layer 6

Takes care of data formatting, encryption, and compression

Application Layer 7

Provides network services to applications (HTTP, FTP, etc.)

OSI

A conceptual framework for network communication divided into 7 layers

PDU (Protocol Data Unit)

The unit of data at each layer of the OSI model

How many layers are in the OSI model?

7

What does OSI stand for?

Open Systems Interconnection

What is a PDU?

Protocol Data Unit (data unit at each layer)

What layer is responsible for the physical transmission of data?

Layer 1 - Physical Layer

What device operates at Layer 1?

Repeater

What layer defines the format of data packets?

Layer 2 - Data Link Layer

What is the PDU at Layer 2 called?

Frame

What layer handles logical addressing (MAC addresses)?

Layer 2 - Data Link Layer

What layer is responsible for routing data packets across networks?

Layer 3 - Network Layer

What is the PDU at Layer 3 called?

Packet

What protocol operates at Layer 3?

IP (Internet Protocol)

What layer establishes, manages, and terminates connections between applications?

Layer 4 - Transport Layer

What is the PDU at Layer 4 called?

Segment (TCP) or Datagram (UDP)

Which protocols operate at Layer 4?

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol)

What layer defines the presentation of data (encryption, compression)?

Layer 5 - Presentation Layer

What layer provides services to applications like file transfer and email?

Layer 6 - Session Layer

What layer interacts directly with user applications?

Layer 7 - Application Layer

Which layer does HTTP operate on?

Layer 7 - Application Layer

What is the benefit of using a layered model for networking?

Promotes modularity, interoperability, and troubleshooting

Briefly describe the concept of encapsulation in the OSI model.

Data is wrapped with header information at each layer as it travels down the stack, and then unwrapped as it travels up the stack at the receiving end.

Flashcards: OSI Model