Examkin

Question

Difficulty: MediumOSI Model Layers and Functions

While analyzing network traffic from a workstation connected to a managed switch, a technician identifies data units formatted with physical source and destination addresses, along with a Frame Check Sequence (FCS) field added to detect transmission errors before passing the data to the physical medium. Which layer of the OSI model is responsible for performing media access control and appending this trailer?

  1. A
    Network Layer
  2. Data Link LayerAnswer
  3. C
    Transport Layer
  4. D
    Physical Layer

Answer

Data Link Layer
The correct answer is the Data Link Layer because Layer 2 of the OSI model operates on frames. It uses Media Access Control (MAC) addresses for local node-to-node delivery and appends a trailer containing the Frame Check Sequence (FCS) to verify frame integrity over the physical link.

Step-by-Step Solution

1
Identify the key components described in the scenario
The scenario mentions physical MAC addresses, media access control, and a Frame Check Sequence (FCS) trailer added for error detection.
Recognizing the specific Protocol Data Unit (PDU) structures and helper fields isolates which layer creates and manages these fields.
2
Map the identified functions to the corresponding OSI layer
Structuring payload data into frames with hardware MAC addresses and appending CRC/FCS trailers occurs at Layer 2.
Layer 2 (Data Link) is explicitly split into the Logical Link Control (LLC) and Media Access Control (MAC) sublayers responsible for frame encapsulation and error detection.

Key Concept

Data Link Layer (Layer 2) encapsulation, MAC addressing, and frame error checking via FCS
Rate this question

Topics

OSI Model Layers and Functions

More questions from this topic