Question 1

Which OSI layer is responsible for end-to-end communication, error recovery, and flow control between hosts?

Accepted Answer

Layer 4 – the Transport layer. It ensures reliable data delivery using protocols like TCP and manages segmentation, sequencing, and acknowledgment.

Question 2

At which OSI layer does a router primarily operate?

Accepted Answer

Layer 3 – the Network layer. Routers use IP addresses to make forwarding decisions between different networks.

Question 3

What is the correct order of the OSI model layers from Layer 1 to Layer 7?

Accepted Answer

Physical, Data Link, Network, Transport, Session, Presentation, Application. A common mnemonic is 'Please Do Not Throw Sausage Pizza Away.'

Question 4

Which OSI layer is responsible for data encryption, compression, and format translation?

Accepted Answer

Layer 6 – the Presentation layer. It translates data between the application and network formats, handling encryption and compression.

Question 5

What Protocol Data Unit (PDU) is used at the OSI Data Link layer?

Accepted Answer

A frame. The Data Link layer encapsulates packets into frames, adding MAC address headers and a trailer for error detection.

CompTIA Network+ Networking Fundamentals

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