When troubleshooting a network problem, browsing through the log of a switch, it is discovered that multiple frames contain errors. In which of the following layers does the problem reside? (Select TWO).
A. Layer 2 B. Layer 3 C. Layer 5 D. Transport layer E. Data link F. Physical layer
Correct Answer: AE
Explanation: Layer 2 of the OSI reference model is the data-link layer. Components of the data-link layer include frame-format, Media Access Control (MAC) addressing, protocol identification and error detection. When data is being sent, it is split into protocol data units (PDUs) as it passes through the layers of the OSI model. The PDUs have different names as they are passed through the layers of the OSI model. In layer 2, the PDU is called a ‘Frame’. The most common protocol specified in the data-link layer is Ethernet and the most common network component in the data-link layer is a network switch. In this question, problems are discovered with Ethernet frames by examining the logs in a network switch. Therefore, for this question, we are working in Layer 2, the data-link layer.