Network+ OSI Model and Data Encapsulation Flashcards

Which OSI layer is responsible for flow control and error recovery using mechanisms like windowing and acknowledgments?

Answer: Transport layer

The Transport layer (Layer 4) provides flow control through windowing and ensures reliable delivery via acknowledgments and retransmission.

A frame is received with a bad FCS value. At which OSI layer is this error detected?

Answer: Data Link layer

The Frame Check Sequence (FCS) is a Data Link layer field used to detect transmission errors in received frames.

Which of the following best describes the role of the Physical layer in the OSI model?

Answer: Converts data to electrical, optical, or radio signals

The Physical layer (Layer 1) defines the transmission of raw bits over a physical medium as electrical, optical, or wireless signals.

An application developer needs to ensure data is formatted consistently for exchange between different systems. Which OSI layer addresses this concern?

Answer: Presentation layer

The Presentation layer (Layer 6) handles data syntax and semantics, ensuring data is in a common format regardless of the source system.

What does a switch primarily use to make forwarding decisions at OSI Layer 2?

Answer: MAC addresses

Switches operate at the Data Link layer and use MAC address tables to forward frames to the correct port.

Which protocol data unit (PDU) is associated with the Data Link layer?

Answer: Frame

The Data Link layer encapsulates packets into frames, adding source and destination MAC addresses along with error-checking fields.

A router receives a packet destined for a remote network. At which OSI layer does the router make its forwarding decision?

Answer: Layer 3

Routers operate at Layer 3 (Network layer), using IP addresses and routing tables to determine the best path for packet forwarding.