Protocol Layering Concepts and TCP/IP Layering ICSSCADA Practice Questions (Page 2)

Questions 6–10

1. 6expert · medium

   A control system engineer is troubleshooting a problem where a PLC is sending data to an HMI, but the HMI is receiving garbled data. The engineer verifies that the IP addresses and TCP ports are correct. The engineer suspects that the issue is at the presentation layer. Which function is performed at the presentation layer?

   • ARouting packets between networks
   • BData formatting and encryption
   • CEstablishing and managing sessions
   • DProviding reliable end-to-end delivery
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2. 7foundation · easy

   When a receiving host processes an incoming frame, which sequence correctly describes the de-encapsulation process?

   • ARemove IP header, then frame header/trailer, then TCP header, then pass data to the application
   • BPass data directly to the application without removing any headers
   • CRemove frame header/trailer, then IP header, then TCP header, then pass data to the application
   • DRemove TCP header, then IP header, then frame header/trailer, then pass data to the application
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4. 8foundation · easy

   In the TCP/IP model, which layer corresponds most directly to the combination of the OSI Session, Presentation, and Application layers?

   • AInternet layer
   • BNetwork Access layer
   • CTransport layer
   • DApplication layer
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5. 9application · medium

   A technician is analyzing a packet capture from a field device that sends a Modbus/TCP request to a controller. The technician sees the request as a TCP segment, then as an IP packet, and finally as an Ethernet frame. Which process describes what happens when the frame reaches the controller?

   • AEncapsulation: the controller adds an Ethernet header, then an IP header, and then a TCP header to the Modbus request.
   • BDe-encapsulation: the controller strips the Ethernet header, then the IP header, and finally the TCP header to retrieve the Modbus request.
   • CThe controller forwards the frame to the application layer without removing any headers.
   • DThe controller replaces the TCP header with an Ethernet header before passing the data to the application.
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6. 10foundation · easy

   Which of the following is a key difference between the OSI and TCP/IP models?

   • AThe TCP/IP model has more layers than the OSI model
   • BThe OSI model has seven layers, while the TCP/IP model has four layers
   • CBoth models have the same number of layers
   • DThe OSI model is based on the TCP/IP protocol suite
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