PERA Level 0 & 1 Technology Overview and Compromise GICSP Practice Questions (Page 2)

Questions 6–10

1. 6application · medium

   A pipeline company uses a PLC to control a pump station. The PLC communicates with a SCADA master over a fiber optic link. The fiber link is cut, but the PLC continues to operate. Which of the following is the MOST likely outcome?

   • AThe PLC will stop the pump and wait for communication to be restored.
   • BThe pump will continue running at its last setpoint indefinitely.
   • CThe PLC will continue to control the pump based on local logic.
   • DThe SCADA master will take over control of the pump.
   Reveal Solution Discussion Select an answer first
2. 7application · medium

   A water treatment facility uses an RTU to monitor and control remote well pumps. The RTU communicates with a central SCADA system over a serial radio link. The RTU reads a pressure transmitter (4-20 mA) and controls a pump start/stop relay. The facility wants to add a new pressure transmitter at the same location. Which of the following is the most important consideration when adding the new transmitter?

   • AVerify that the radio link has sufficient bandwidth to transmit the additional data point.
   • BConfirm that the new transmitter is compatible with the existing pump's relay output.
   • CEnsure the RTU has an available analog input channel and that the channel is configured for the same signal type (e.g., 4-20 mA) as the transmitter.
   • DEnsure that the new transmitter has the same measurement range as the existing one.
   Reveal Solution Discussion Select an answer first
4. 8expert · medium

   A power plant has a DCS that controls a steam turbine. The DCS receives speed and vibration signals from sensors. An attacker has compromised the DCS and can modify the vibration sensor scaling. The attacker wants to cause a turbine trip. Which of the following scaling changes would MOST likely cause a trip?

   • ADecrease the scaling of the speed sensor so the speed reading is lower than actual.
   • BDecrease the scaling so the vibration reading is lower than actual.
   • CIncrease the scaling of the speed sensor so the speed reading is higher than actual.
   • DIncrease the scaling so the vibration reading is higher than actual.
   Reveal Solution Discussion Select an answer first
5. 9foundation · easy

   Which of the following is a potential attack vector that could compromise a Level 1 PLC?

   • AA denial-of-service attack on the enterprise email server
   • BMalicious firmware update delivered over the control network
   • CPhysical tampering with a temperature sensor's wiring
   • DA SQL injection attack on a corporate website
   Reveal Solution Discussion Select an answer first
6. 10application · medium

   A power plant uses a DCS to control a boiler. The DCS controllers communicate with field devices over a Profibus network. The DCS reads a pressure transmitter (4-20 mA) and controls a fuel valve. The plant has experienced intermittent communication failures with the Profibus network. Which of the following is the most likely cause?

   • AThe pressure transmitter is not providing a correct 4-20 mA signal.
   • BThe fuel valve is not responding correctly to the control signal.
   • CThe DCS controller's power supply is failing.
   • DThe Profibus cable is not terminated correctly.
   Reveal Solution Discussion Select an answer first