Q.1 What does SCADA stand for?
Supervisory Control And Data Acquisition
Standard Control And Data Analysis
System Control And Data Application
Supervised Control And Data Algorithm
Explanation - SCADA is an acronym for Supervisory Control And Data Acquisition, a system that monitors and controls industrial processes.
Correct answer is: Supervisory Control And Data Acquisition
Q.2 Which device is primarily responsible for collecting sensor data in a SCADA system?
Human-Machine Interface (HMI)
Programmable Logic Controller (PLC)
RTU (Remote Terminal Unit)
SCADA Master Server
Explanation - RTUs are field devices that gather data from sensors and send it to the SCADA master.
Correct answer is: RTU (Remote Terminal Unit)
Q.3 What is the main purpose of the HMI in SCADA?
To execute control logic
To provide a graphical interface for operators
To collect data from field devices
To store long-term data history
Explanation - HMI displays data and allows operators to interact with the process.
Correct answer is: To provide a graphical interface for operators
Q.4 Which protocol is most commonly used for communication between SCADA and PLCs?
Modbus TCP
HTTP
SMTP
FTP
Explanation - Modbus TCP/IP is widely used for SCADA-PLC communication due to its simplicity and reliability.
Correct answer is: Modbus TCP
Q.5 In SCADA, what does RTU stand for?
Real-Time Unit
Remote Terminal Unit
Rapid Transfer Utility
Relay Transfer Unit
Explanation - RTU is a field device that interfaces sensors and actuators with the SCADA master.
Correct answer is: Remote Terminal Unit
Q.6 Which of the following is NOT a typical function of a SCADA system?
Data acquisition
Process control
Human resource management
Alarms and notifications
Explanation - SCADA systems focus on process control, not HR functions.
Correct answer is: Human resource management
Q.7 Which network layer protocol is used by Modbus TCP to encapsulate Modbus frames?
UDP
IP
TCP
HTTP
Explanation - Modbus TCP uses the TCP/IP stack to transmit Modbus frames.
Correct answer is: TCP
Q.8 What is the primary advantage of using OPC-UA over older SCADA protocols?
Higher bandwidth
Simpler installation
Enhanced security and platform independence
Lower cost
Explanation - OPC-UA offers strong authentication, encryption, and works across platforms.
Correct answer is: Enhanced security and platform independence
Q.9 Which of these devices would typically be used to provide redundant communication paths in a SCADA network?
HMI
RTU
Redundant Ethernet Switch
PLC
Explanation - Redundant switches ensure continuous network connectivity even if one link fails.
Correct answer is: Redundant Ethernet Switch
Q.10 What does the term 'data historian' refer to in SCADA?
A device that records long‑term data for trend analysis
An algorithm that predicts future trends
A backup power supply
A security audit tool
Explanation - A data historian archives time‑stamped data for analysis and reporting.
Correct answer is: A device that records long‑term data for trend analysis
Q.11 Which communication protocol is specifically designed for industrial wireless networks?
Wi‑Fi 802.11
Zigbee
WirelessHART
Bluetooth
Explanation - WirelessHART is tailored for industrial control with low power and reliability.
Correct answer is: WirelessHART
Q.12 Which of the following best describes 'local loop' in SCADA?
The communication path between the SCADA master and a PLC via Ethernet
The physical wiring between a sensor and an RTU
The backup link used during network failure
The path between two HMIs
Explanation - Local loop refers to the field wiring that connects sensors to an RTU.
Correct answer is: The physical wiring between a sensor and an RTU
Q.13 In a SCADA system, which component typically handles the scheduling of automated tasks?
Human-Machine Interface
PLC
SCADA Server
RTU
Explanation - The SCADA server manages timed events and task scheduling.
Correct answer is: SCADA Server
Q.14 What is the main purpose of a 'watchdog timer' in PLCs?
To detect network outages
To monitor software faults and reset the PLC if it stalls
To schedule periodic tasks
To provide a graphical interface for operators
Explanation - A watchdog timer restarts the PLC if the firmware fails to reset it within a set time.
Correct answer is: To monitor software faults and reset the PLC if it stalls
Q.15 Which of the following is NOT a typical data type used in SCADA communications?
Boolean
Real
Complex
String
Explanation - SCADA uses Boolean, integer, real, and string data types; complex numbers are rarely used.
Correct answer is: Complex
Q.16 What is the main security risk associated with legacy SCADA protocols like Modbus TCP?
They use encrypted communication by default
They have no built‑in authentication or encryption
They require too many computational resources
They are too expensive to deploy
Explanation - Legacy protocols lack security features, making them vulnerable to attacks.
Correct answer is: They have no built‑in authentication or encryption
Q.17 Which layer of the OSI model does Ethernet operate in?
Physical
Data Link
Network
Transport
Explanation - Ethernet is a Data Link layer technology that handles framing and MAC addressing.
Correct answer is: Data Link
Q.18 Which of the following is a characteristic of a 'distributed control system (DCS)' compared to SCADA?
It uses a single master computer
It typically controls processes at a single site with local PLCs
It relies solely on wireless communication
It cannot interface with HMIs
Explanation - DCS integrates many PLCs locally, whereas SCADA often spans multiple sites via centralized servers.
Correct answer is: It typically controls processes at a single site with local PLCs
Q.19 What is the purpose of 'alarms' in SCADA?
To record historical data
To notify operators of abnormal conditions
To encrypt network traffic
To schedule backups
Explanation - Alarms alert operators when variables exceed set thresholds.
Correct answer is: To notify operators of abnormal conditions
Q.20 Which communication medium is NOT typically used in SCADA?
Serial RS‑485
Fiber optic cable
Satellite links
Soldered copper wires
Explanation - SCADA uses communication media like RS‑485, fiber, and satellite; soldered wires are not a medium.
Correct answer is: Soldered copper wires
Q.21 In a SCADA system, which component is responsible for data acquisition from the field?
SCADA server
PLC/RTU
HMI
Data historian
Explanation - PLCs and RTUs read sensor signals and provide data to the SCADA server.
Correct answer is: PLC/RTU
Q.22 Which protocol provides secure, encrypted communication over TCP/IP for SCADA?
Modbus TCP
OPC-UA
DNP3
BACnet
Explanation - OPC-UA includes built‑in authentication and encryption.
Correct answer is: OPC-UA
Q.23 What does 'RTU' stand for in SCADA?
Real‑Time Unit
Remote Terminal Unit
Rapid Transmission Unit
Redundant Transfer Unit
Explanation - An RTU is a field device that communicates with the SCADA master.
Correct answer is: Remote Terminal Unit
Q.24 Which of the following is a typical data format used in SCADA communications?
JSON
CSV
XML
All of the above
Explanation - SCADA systems can use various data formats, including JSON, CSV, and XML.
Correct answer is: All of the above
Q.25 Which of these is a primary reason for using Modbus over DNP3?
Higher security
Greater reliability in harsh environments
Simplicity and widespread adoption
Native support for OPC-UA
Explanation - Modbus is simple and widely used, making it a common choice for basic SCADA setups.
Correct answer is: Simplicity and widespread adoption
Q.26 What type of device is a 'PLC'?
Programmable Logic Controller
Programmable Light Controller
Power Line Controller
Peripheral Logic Component
Explanation - A PLC is a rugged computer used to control industrial processes.
Correct answer is: Programmable Logic Controller
Q.27 Which SCADA component provides graphical visualization?
RTU
PLC
HMI
Data Historian
Explanation - Human‑Machine Interfaces display process information graphically.
Correct answer is: HMI
Q.28 What does 'DNP3' stand for?
Distributed Network Protocol 3
Distributed Network Protocol 3
Distributed Network Protocol 3
Distributed Network Protocol 3
Explanation - DNP3 is a protocol used for communication in SCADA systems.
Correct answer is: Distributed Network Protocol 3
Q.29 Which layer of the OSI model handles routing of data?
Physical
Data Link
Network
Transport
Explanation - The Network layer manages logical addressing and routing.
Correct answer is: Network
Q.30 What is a common method to secure SCADA communication over the internet?
Using VPN tunnels
Leaving ports open
Relying on Modbus TCP security
Using unencrypted HTTP
Explanation - VPNs provide secure encrypted tunnels for SCADA traffic.
Correct answer is: Using VPN tunnels
Q.31 Which of the following is a security best practice for SCADA?
Using default usernames and passwords
Disabling firewalls on SCADA servers
Implementing role‑based access control
Leaving all ports open to the internet
Explanation - RBAC limits user access to only necessary functions.
Correct answer is: Implementing role‑based access control
Q.32 What does 'RTU' use to connect to the SCADA master over long distances?
Ethernet
Serial over fiber
Wi‑Fi
Bluetooth
Explanation - Serial over fiber allows long‑range data transmission for RTUs.
Correct answer is: Serial over fiber
Q.33 Which protocol is specifically designed for secure SCADA communications?
Modbus TCP
DNP3 Secure
BACnet/IP
OPC Classic
Explanation - DNP3 Secure adds authentication and encryption to the base protocol.
Correct answer is: DNP3 Secure
Q.34 What is the primary difference between a PLC and an RTU?
PLCs are used for control, RTUs for data collection
RTUs are always wireless
PLCs have no local I/O
RTUs cannot be networked
Explanation - PLCs execute control logic; RTUs focus on data acquisition and remote control.
Correct answer is: PLCs are used for control, RTUs for data collection
Q.35 Which of these is NOT a typical SCADA alarm type?
Hard fault
Soft fault
Normal operation
Critical alarm
Explanation - Alarms signal abnormal conditions; normal operation is not an alarm.
Correct answer is: Normal operation
Q.36 In SCADA, what does 'historian' store?
Real‑time process data
Only current alarms
Historical time‑series data
User credentials
Explanation - The historian archives data over long periods for analysis.
Correct answer is: Historical time‑series data
Q.37 Which SCADA protocol can be used over UDP?
Modbus TCP
DNP3
OPC-UA
BACnet/IP
Explanation - DNP3 can operate over UDP for low‑latency communication.
Correct answer is: DNP3
Q.38 What is the role of the 'master' in a SCADA architecture?
Collect data from field devices
Control field devices directly
Serve as a backup power source
Provide human interface only
Explanation - The master gathers data, processes it, and sends commands back to field devices.
Correct answer is: Collect data from field devices
Q.39 Which SCADA component is responsible for setting thresholds for alarms?
PLC
RTU
HMI
SCADA Server
Explanation - The SCADA server defines alarm conditions and thresholds.
Correct answer is: SCADA Server
Q.40 Which of the following is NOT a typical SCADA communication protocol?
Modbus
DNP3
HTTP
OPC-UA
Explanation - HTTP is a web protocol, not typically used for SCADA control.
Correct answer is: HTTP
Q.41 What type of network topology is commonly used in SCADA to connect RTUs?
Star
Ring
Mesh
All of the above
Explanation - Star, ring, and mesh topologies can all be employed depending on reliability needs.
Correct answer is: All of the above
Q.42 Which of these is a feature of OPC‑UA that enhances security?
Built‑in authentication
No encryption
Only supports IPv4
Requires proprietary hardware
Explanation - OPC‑UA supports authentication and encryption for secure data transfer.
Correct answer is: Built‑in authentication
Q.43 Which of the following is a type of SCADA attack vector?
SQL injection on HMI database
Physical tampering with RTU cables
Denial of Service on the SCADA server
All of the above
Explanation - SCADA can be compromised via software, hardware, or network attacks.
Correct answer is: All of the above
Q.44 What does 'RTU' typically support in terms of communication protocols?
Modbus TCP only
Modbus RTU and DNP3
Only OPC-UA
None; RTUs do not use protocols
Explanation - RTUs often support multiple field protocols for compatibility.
Correct answer is: Modbus RTU and DNP3
Q.45 Which device in SCADA is responsible for executing control logic in real time?
PLC
RTU
HMI
SCADA Server
Explanation - PLCs execute real‑time control logic locally.
Correct answer is: PLC
Q.46 Which SCADA communication protocol can use both TCP and UDP?
Modbus TCP
DNP3
OPC-UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transport layers.
Correct answer is: DNP3
Q.47 What does the abbreviation 'HMI' stand for?
Human‑Machine Interface
High‑Speed Modbus Interface
Hardware Management Interface
Hierarchical Monitoring Instance
Explanation - HMI provides visual feedback and controls for operators.
Correct answer is: Human‑Machine Interface
Q.48 Which layer of the OSI model is responsible for end‑to‑end error checking in Ethernet?
Physical
Data Link
Transport
Application
Explanation - Transport layer protocols like TCP provide error detection and recovery.
Correct answer is: Transport
Q.49 What is a 'field bus' in the context of SCADA?
A network connecting PLCs to the SCADA server
A bus for connecting field devices to RTUs
A bus used in data historians
A type of HMI display
Explanation - Field buses (e.g., PROFIBUS) link sensors and actuators to RTUs.
Correct answer is: A bus for connecting field devices to RTUs
Q.50 Which of the following is an advantage of using OPC-UA over Modbus?
Lower bandwidth usage
Built‑in security and platform independence
Simplicity
No need for encryption
Explanation - OPC‑UA supports authentication, encryption, and cross‑platform communication.
Correct answer is: Built‑in security and platform independence
Q.51 In SCADA, what is the purpose of 'redundancy'?
To store backup data
To provide duplicate communication paths or servers
To speed up data processing
To increase alarm frequency
Explanation - Redundancy ensures system availability in case of failure.
Correct answer is: To provide duplicate communication paths or servers
Q.52 Which type of attack specifically targets SCADA networks by exploiting unsecured remote access?
Phishing
Man‑in‑the‑Middle
Ransomware
Brute‑force login
Explanation - Brute‑force attacks can compromise SCADA systems lacking strong authentication.
Correct answer is: Brute‑force login
Q.53 What is the main benefit of using a 'data historian' in SCADA?
Real‑time process control
Long‑term trend analysis
Improving network speed
Providing user training
Explanation - Historians archive data for analysis over extended periods.
Correct answer is: Long‑term trend analysis
Q.54 Which protocol is known for its 'transparent' communication in SCADA?
Modbus
DNP3
OPC-UA
BACnet/IP
Explanation - DNP3 is designed for reliable, transparent data exchange in utilities.
Correct answer is: DNP3
Q.55 What does 'RTU' stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - RTU is a field device that connects sensors to SCADA.
Correct answer is: Remote Terminal Unit
Q.56 Which of these is NOT a typical SCADA network topology?
Star
Mesh
Tree
Bus
Explanation - Tree is not commonly used in SCADA due to its single point of failure.
Correct answer is: Tree
Q.57 What is the primary function of a PLC in SCADA?
Data logging only
Executing control logic
User authentication
Providing internet connectivity
Explanation - PLCs process input signals and control outputs in real time.
Correct answer is: Executing control logic
Q.58 Which protocol is used for SCADA communication over the internet with security enhancements?
Modbus TCP
OPC UA over TLS
DNP3 over UDP
BACnet/IP
Explanation - OPC‑UA can run over TLS for secure encrypted communication.
Correct answer is: OPC UA over TLS
Q.59 What does 'Modbus RTU' refer to?
A TCP variant of Modbus
A serial version of Modbus
An OPC-UA protocol
A DNP3 extension
Explanation - Modbus RTU uses RS‑485 serial communication.
Correct answer is: A serial version of Modbus
Q.60 Which of the following is a key benefit of using OPC‑UA in SCADA?
Low power consumption
Platform independence and security
Only works over Ethernet
Requires proprietary hardware
Explanation - OPC‑UA runs on many OSes and includes built‑in security.
Correct answer is: Platform independence and security
Q.61 What is a 'master–slave' relationship in SCADA?
A PLC controlling an HMI
A SCADA server requesting data from RTUs
A redundant SCADA system
An HMI controlling a PLC
Explanation - The master initiates communication, while slaves respond.
Correct answer is: A SCADA server requesting data from RTUs
Q.62 Which SCADA component is typically used to provide a graphical interface for operators?
PLC
RTU
HMI
Data historian
Explanation - HMI displays graphical representations of process data.
Correct answer is: HMI
Q.63 What is the main purpose of 'alarms' in SCADA?
To trigger automatic shutdown
To notify operators of abnormal conditions
To store historical data
To provide network routing
Explanation - Alarms alert operators to deviations from normal operation.
Correct answer is: To notify operators of abnormal conditions
Q.64 Which of the following is not a typical SCADA data type?
Boolean
Integer
Complex
String
Explanation - SCADA rarely uses complex data types; it mainly uses numeric and string types.
Correct answer is: Complex
Q.65 Which protocol is specifically designed for secure SCADA communications?
DNP3 Secure
Modbus TCP
OPC Classic
BACnet/IP
Explanation - DNP3 Secure adds authentication and encryption to the standard DNP3.
Correct answer is: DNP3 Secure
Q.66 Which component of a SCADA system collects data from field devices?
SCADA server
RTU
HMI
PLC
Explanation - RTUs gather sensor data and communicate it to the SCADA server.
Correct answer is: RTU
Q.67 What does the abbreviation 'DNP3' stand for?
Distributed Network Protocol 3
Distributed Network Protocol 3
Distributed Network Protocol 3
Distributed Network Protocol 3
Explanation - DNP3 is a widely used protocol in SCADA for data exchange.
Correct answer is: Distributed Network Protocol 3
Q.68 Which of the following best describes a 'PLC'?
Programmable Logic Controller
Programmable Light Controller
Power Line Controller
Peripheral Logic Component
Explanation - A PLC is a rugged computer that controls industrial processes.
Correct answer is: Programmable Logic Controller
Q.69 What is a 'data historian' used for in SCADA?
To monitor network traffic
To log data for trend analysis
To provide graphical displays
To control field devices
Explanation - A data historian records time‑series data for analysis and reporting.
Correct answer is: To log data for trend analysis
Q.70 Which of these is a key benefit of using OPC-UA in SCADA?
Low power consumption
Platform independence and security
Only works over Ethernet
Requires proprietary hardware
Explanation - OPC‑UA runs on many operating systems and includes built‑in security.
Correct answer is: Platform independence and security
Q.71 What is the main difference between a PLC and an RTU?
PLCs are used for control, RTUs for data collection
RTUs are always wireless
PLCs have no local I/O
RTUs cannot be networked
Explanation - PLCs execute control logic; RTUs focus on data acquisition.
Correct answer is: PLCs are used for control, RTUs for data collection
Q.72 Which of the following is a typical SCADA communication protocol?
Modbus
DNP3
OPC-UA
All of the above
Explanation - All three are common SCADA protocols.
Correct answer is: All of the above
Q.73 Which layer of the OSI model handles the physical transmission of data?
Physical
Data Link
Transport
Application
Explanation - The Physical layer deals with electrical, optical, or radio signals.
Correct answer is: Physical
Q.74 What is the primary advantage of using a 'historian' in SCADA?
Real‑time monitoring
Long‑term data storage
Alarm generation
Device configuration
Explanation - The historian archives data for future analysis.
Correct answer is: Long‑term data storage
Q.75 Which protocol can be used for SCADA communication over the internet with built‑in security?
Modbus TCP
OPC UA over TLS
DNP3 over UDP
BACnet/IP
Explanation - OPC‑UA can be secured with TLS for encrypted communication.
Correct answer is: OPC UA over TLS
Q.76 What does 'RTU' stand for in SCADA terminology?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - RTUs interface sensors and actuators to the SCADA network.
Correct answer is: Remote Terminal Unit
Q.77 Which of the following is NOT a SCADA protocol?
Modbus
DNP3
HTTP
OPC-UA
Explanation - HTTP is a web protocol, not typically used for SCADA control.
Correct answer is: HTTP
Q.78 Which of the following devices provides a graphical interface for operators?
PLC
RTU
HMI
Data historian
Explanation - HMI displays process information graphically.
Correct answer is: HMI
Q.79 What is the main purpose of a SCADA alarm system?
To notify operators of abnormal conditions
To store data in a historian
To control field devices
To provide remote access
Explanation - Alarms alert operators to deviations from normal operation.
Correct answer is: To notify operators of abnormal conditions
Q.80 Which SCADA protocol uses TCP/IP for data transmission?
Modbus TCP
Modbus RTU
DNP3
OPC Classic
Explanation - Modbus TCP encapsulates Modbus frames in TCP/IP packets.
Correct answer is: Modbus TCP
Q.81 What does 'PLC' stand for?
Programmable Logic Controller
Programmable Light Controller
Power Line Controller
Peripheral Logic Component
Explanation - A PLC is a rugged computer for controlling industrial processes.
Correct answer is: Programmable Logic Controller
Q.82 Which protocol is commonly used for SCADA communication over serial lines?
Modbus RTU
Modbus TCP
DNP3
OPC-UA
Explanation - Modbus RTU works over RS‑485 serial links.
Correct answer is: Modbus RTU
Q.83 What does 'RTU' stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - An RTU interfaces field sensors and actuators to SCADA.
Correct answer is: Remote Terminal Unit
Q.84 Which of the following is a feature of OPC-UA?
Built‑in encryption
Only works on Windows
Requires proprietary hardware
No support for real‑time control
Explanation - OPC‑UA supports authentication and encryption.
Correct answer is: Built‑in encryption
Q.85 What is a 'data historian' used for in SCADA?
To control field devices
To log and analyze process data over time
To provide a user interface
To secure the network
Explanation - Historians store long‑term data for trend analysis.
Correct answer is: To log and analyze process data over time
Q.86 Which SCADA communication protocol can operate over UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transport.
Correct answer is: DNP3
Q.87 What is the main difference between a PLC and an RTU?
PLCs execute control logic, RTUs gather data
RTUs are always wireless
PLCs have no local I/O
RTUs cannot be networked
Explanation - PLCs control processes locally; RTUs focus on data acquisition.
Correct answer is: PLCs execute control logic, RTUs gather data
Q.88 Which layer of the OSI model is responsible for end‑to‑end error checking?
Transport
Data Link
Network
Physical
Explanation - Transport layer protocols like TCP provide error detection.
Correct answer is: Transport
Q.89 Which of the following is NOT a typical SCADA protocol?
Modbus
DNP3
HTTP
OPC-UA
Explanation - HTTP is a web protocol, not used for SCADA control.
Correct answer is: HTTP
Q.90 What does 'RTU' stand for in SCADA terminology?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - An RTU connects field devices to the SCADA network.
Correct answer is: Remote Terminal Unit
Q.91 Which component of a SCADA system is primarily responsible for data acquisition?
PLC
RTU
HMI
SCADA Server
Explanation - RTUs gather sensor data and transmit it to the SCADA master.
Correct answer is: RTU
Q.92 Which of the following is an advantage of using OPC-UA over Modbus?
Higher bandwidth usage
Simpler configuration
Built‑in security and platform independence
Lower cost
Explanation - OPC‑UA includes authentication, encryption, and works across platforms.
Correct answer is: Built‑in security and platform independence
Q.93 Which protocol is specifically designed for industrial wireless networks?
WirelessHART
Modbus TCP
DNP3
OPC-UA
Explanation - WirelessHART is tailored for industrial control with low power and reliability.
Correct answer is: WirelessHART
Q.94 What is the main purpose of a 'historian' in SCADA?
To monitor network traffic
To store long‑term data for trend analysis
To provide user training
To control field devices
Explanation - The historian archives data for future analysis.
Correct answer is: To store long‑term data for trend analysis
Q.95 Which layer of the OSI model is responsible for addressing and routing?
Physical
Data Link
Network
Transport
Explanation - The Network layer manages logical addressing and routing decisions.
Correct answer is: Network
Q.96 What does SCADA stand for?
Supervisory Control And Data Acquisition
System Control And Data Analysis
Standard Control And Data Application
Supervised Control And Data Algorithm
Explanation - SCADA is an acronym for Supervisory Control And Data Acquisition.
Correct answer is: Supervisory Control And Data Acquisition
Q.97 Which device in SCADA is typically used to provide a graphical interface for operators?
RTU
PLC
HMI
Data Historian
Explanation - HMIs display process data graphically for operators.
Correct answer is: HMI
Q.98 Which protocol is used for SCADA communication over the internet with built‑in security?
Modbus TCP
OPC UA over TLS
DNP3 over UDP
BACnet/IP
Explanation - OPC‑UA can run over TLS for encrypted communication.
Correct answer is: OPC UA over TLS
Q.99 What is the main purpose of a SCADA alarm system?
To notify operators of abnormal conditions
To provide a user interface
To store long‑term data
To control field devices
Explanation - Alarms alert operators to deviations from normal operation.
Correct answer is: To notify operators of abnormal conditions
Q.100 Which of the following is NOT a typical SCADA protocol?
Modbus
DNP3
OPC UA
HTTP
Explanation - HTTP is a web protocol, not used for SCADA control.
Correct answer is: HTTP
Q.101 Which of the following is an example of a SCADA communication protocol?
Modbus
DNP3
OPC UA
All of the above
Explanation - All are widely used SCADA protocols.
Correct answer is: All of the above
Q.102 Which layer of the OSI model handles data link and MAC addressing?
Physical
Data Link
Network
Transport
Explanation - Data link layer manages MAC addresses and framing.
Correct answer is: Data Link
Q.103 What does 'RTU' stand for in SCADA systems?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - An RTU is a field device that collects sensor data and communicates with the SCADA master.
Correct answer is: Remote Terminal Unit
Q.104 Which of the following is NOT a typical SCADA network topology?
Star
Ring
Mesh
Tree
Explanation - Tree topology is less common in SCADA due to single point of failure concerns.
Correct answer is: Tree
Q.105 Which protocol is known for its 'transparent' communication in SCADA?
Modbus
DNP3
OPC-UA
BACnet/IP
Explanation - DNP3 is designed for reliable, transparent data exchange.
Correct answer is: DNP3
Q.106 What is the role of the SCADA master server?
Collects data from field devices
Controls PLCs directly
Provides graphical displays
Logs historical data
Explanation - The master gathers data, processes it, and sends commands to field devices.
Correct answer is: Collects data from field devices
Q.107 Which protocol provides secure, encrypted communication over TCP/IP for SCADA?
Modbus TCP
OPC-UA
DNP3
BACnet/IP
Explanation - OPC-UA includes authentication and encryption.
Correct answer is: OPC-UA
Q.108 Which of the following is a common security measure in SCADA?
Using default credentials
Disabling firewalls
Implementing role‑based access control
Leaving all ports open
Explanation - RBAC limits user access to necessary functions.
Correct answer is: Implementing role‑based access control
Q.109 Which SCADA component provides real‑time control logic execution?
PLC
RTU
HMI
SCADA Server
Explanation - PLCs perform real‑time control in industrial processes.
Correct answer is: PLC
Q.110 What is a key feature of OPC‑UA that enhances security?
Built‑in authentication
No encryption
Only supports IPv4
Requires proprietary hardware
Explanation - OPC‑UA supports authentication and encryption for secure communication.
Correct answer is: Built‑in authentication
Q.111 Which protocol can be used for SCADA communication over the internet with built‑in security?
Modbus TCP
OPC UA over TLS
DNP3 over UDP
BACnet/IP
Explanation - OPC‑UA can use TLS for secure, encrypted communication.
Correct answer is: OPC UA over TLS
Q.112 What does SCADA stand for?
Supervisory Control And Data Acquisition
System Control And Data Analysis
Standard Control And Data Application
Supervised Control And Data Algorithm
Explanation - SCADA stands for Supervisory Control And Data Acquisition.
Correct answer is: Supervisory Control And Data Acquisition
Q.113 Which device is used to gather data from sensors and transmit it to SCADA servers?
PLC
RTU
HMI
Data Historian
Explanation - RTUs collect field data and communicate with SCADA servers.
Correct answer is: RTU
Q.114 What is a primary advantage of using OPC-UA over legacy SCADA protocols?
Higher bandwidth usage
Simpler configuration
Enhanced security and platform independence
Lower cost
Explanation - OPC‑UA offers built‑in authentication, encryption, and cross‑platform support.
Correct answer is: Enhanced security and platform independence
Q.115 Which communication protocol is commonly used for SCADA over serial lines?
Modbus RTU
Modbus TCP
DNP3
OPC-UA
Explanation - Modbus RTU operates over RS‑485 serial links.
Correct answer is: Modbus RTU
Q.116 What does RTU stand for in SCADA systems?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - RTU is a field device that connects sensors and actuators to SCADA.
Correct answer is: Remote Terminal Unit
Q.117 Which SCADA protocol can run over both TCP and UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transport layers.
Correct answer is: DNP3
Q.118 What is the main role of the HMI in SCADA?
Data acquisition
Process control
Graphical display and operator interaction
Long‑term data storage
Explanation - HMIs provide visual interfaces for operators.
Correct answer is: Graphical display and operator interaction
Q.119 Which layer of the OSI model is responsible for framing and error checking at the data link level?
Physical
Data Link
Network
Transport
Explanation - Data Link layer manages framing, MAC addresses, and error detection.
Correct answer is: Data Link
Q.120 What is a primary security risk of using Modbus TCP without encryption?
No data integrity
No authentication
High latency
Limited data types
Explanation - Modbus TCP lacks built‑in authentication, making it vulnerable.
Correct answer is: No authentication
Q.121 Which of the following is an example of a field bus used in SCADA?
Ethernet/IP
PROFIBUS
Wi‑Fi
Bluetooth
Explanation - PROFIBUS is a common field bus that links sensors and actuators.
Correct answer is: PROFIBUS
Q.122 Which SCADA component is responsible for logging historical data?
PLC
RTU
Data Historian
HMI
Explanation - Data historians archive time‑series data for long‑term analysis.
Correct answer is: Data Historian
Q.123 What is the main advantage of using a redundant SCADA server?
Lower cost
Simpler configuration
Increased system availability
Improved data compression
Explanation - Redundancy ensures the system continues operating if one server fails.
Correct answer is: Increased system availability
Q.124 Which SCADA protocol can be secured using TLS encryption?
Modbus TCP
OPC-UA
DNP3
BACnet/IP
Explanation - OPC‑UA supports TLS for encrypted communication.
Correct answer is: OPC-UA
Q.125 What is a typical use of a 'watchdog timer' in PLCs?
Monitor network traffic
Detect software faults and reset PLC
Schedule tasks
Provide graphical display
Explanation - Watchdog timers ensure PLC recovers from software stalls.
Correct answer is: Detect software faults and reset PLC
Q.126 Which of the following is NOT a typical SCADA protocol?
Modbus
DNP3
BACnet/IP
SSH
Explanation - SSH is a secure shell protocol, not a SCADA communication protocol.
Correct answer is: SSH
Q.127 Which layer of the OSI model deals with end‑to‑end error recovery and flow control?
Transport
Data Link
Network
Physical
Explanation - The Transport layer provides reliability and flow control.
Correct answer is: Transport
Q.128 What does 'RTU' stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - RTUs interface sensors and actuators to SCADA networks.
Correct answer is: Remote Terminal Unit
Q.129 Which protocol is most widely used for SCADA communication over Ethernet?
Modbus TCP
Modbus RTU
DNP3
OPC Classic
Explanation - Modbus TCP is the common Ethernet‑based SCADA protocol.
Correct answer is: Modbus TCP
Q.130 Which SCADA component handles real‑time control of field devices?
PLC
RTU
HMI
SCADA Server
Explanation - PLCs execute control logic locally in real time.
Correct answer is: PLC
Q.131 Which SCADA protocol can use both TCP and UDP transport layers?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP.
Correct answer is: DNP3
Q.132 What is the primary advantage of using OPC-UA in SCADA systems?
High bandwidth
Platform independence and security
Low cost
Only supports local networks
Explanation - OPC‑UA runs across platforms and includes authentication and encryption.
Correct answer is: Platform independence and security
Q.133 Which of the following is a typical SCADA architecture component?
RTU
PLC
HMI
All of the above
Explanation - All are core components of SCADA architecture.
Correct answer is: All of the above
Q.134 What does the 'master' in SCADA architecture do?
Collects data from field devices
Controls field devices directly
Provides user interface
Stores historical data
Explanation - The master aggregates data and issues control commands.
Correct answer is: Collects data from field devices
Q.135 Which SCADA protocol is designed for secure, encrypted communication?
Modbus TCP
DNP3 Secure
OPC Classic
BACnet/IP
Explanation - DNP3 Secure adds authentication and encryption to DNP3.
Correct answer is: DNP3 Secure
Q.136 Which layer of the OSI model is responsible for logical addressing and routing?
Network
Transport
Data Link
Physical
Explanation - The Network layer handles IP addresses and routing decisions.
Correct answer is: Network
Q.137 What is the main advantage of using a redundant SCADA system?
Increased reliability
Lower cost
Simpler configuration
Reduced bandwidth usage
Explanation - Redundancy ensures continuous operation during failures.
Correct answer is: Increased reliability
Q.138 Which protocol is specifically designed for industrial wireless networks?
WirelessHART
Modbus TCP
DNP3
OPC UA
Explanation - WirelessHART is tailored for industrial control.
Correct answer is: WirelessHART
Q.139 What does SCADA stand for?
Supervisory Control And Data Acquisition
System Control And Data Analysis
Standard Control And Data Application
Supervised Control And Data Algorithm
Explanation - SCADA is Supervisory Control And Data Acquisition.
Correct answer is: Supervisory Control And Data Acquisition
Q.140 Which device is primarily responsible for collecting sensor data in a SCADA system?
RTU
PLC
HMI
SCADA Server
Explanation - RTUs gather data from sensors and send it to the SCADA server.
Correct answer is: RTU
Q.141 Which of the following protocols is used for SCADA communication over the internet with built‑in security?
Modbus TCP
OPC UA over TLS
DNP3 over UDP
BACnet/IP
Explanation - OPC‑UA can run over TLS for encrypted communication.
Correct answer is: OPC UA over TLS
Q.142 What is a typical use of a 'historian' in SCADA?
To log and analyze process data over time
To provide user interfaces
To control field devices
To monitor network traffic
Explanation - The historian archives time‑series data for trend analysis.
Correct answer is: To log and analyze process data over time
Q.143 Which protocol can run over both TCP and UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP.
Correct answer is: DNP3
Q.144 What does RTU stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - An RTU is a field device that collects data and communicates with SCADA.
Correct answer is: Remote Terminal Unit
Q.145 Which SCADA protocol is most commonly used for industrial automation over serial lines?
Modbus RTU
Modbus TCP
DNP3
OPC-UA
Explanation - Modbus RTU operates over RS‑485 serial communication.
Correct answer is: Modbus RTU
Q.146 What is the primary difference between a PLC and an RTU?
PLCs are used for control, RTUs for data collection
RTUs are always wireless
PLCs have no local I/O
RTUs cannot be networked
Explanation - PLCs execute control logic; RTUs focus on data acquisition.
Correct answer is: PLCs are used for control, RTUs for data collection
Q.147 Which layer of the OSI model handles end‑to‑end error checking and flow control?
Transport
Data Link
Network
Physical
Explanation - The Transport layer ensures reliable data transmission.
Correct answer is: Transport
Q.148 What is a key security feature of OPC-UA?
Built‑in authentication
No encryption
Only supports IPv6
Requires proprietary hardware
Explanation - OPC‑UA supports authentication and encryption for secure data exchange.
Correct answer is: Built‑in authentication
Q.149 Which SCADA protocol is commonly used for secure communications in critical infrastructure?
Modbus TCP
DNP3 Secure
OPC Classic
BACnet/IP
Explanation - DNP3 Secure includes authentication and encryption.
Correct answer is: DNP3 Secure
Q.150 Which device in SCADA provides a graphical interface for operators?
RTU
PLC
HMI
Data Historian
Explanation - HMIs display process information graphically for operators.
Correct answer is: HMI
Q.151 What is the role of the SCADA master server?
Collects data from field devices
Controls PLCs directly
Provides graphical displays
Logs historical data
Explanation - The master aggregates data and issues commands to field devices.
Correct answer is: Collects data from field devices
Q.152 Which protocol provides secure, encrypted communication over TCP/IP for SCADA?
Modbus TCP
OPC-UA
DNP3
BACnet/IP
Explanation - OPC‑UA includes authentication and encryption.
Correct answer is: OPC-UA
Q.153 Which of the following is a typical SCADA protocol?
Modbus
DNP3
OPC-UA
All of the above
Explanation - All are widely used SCADA protocols.
Correct answer is: All of the above
Q.154 What does the abbreviation 'RTU' stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - An RTU interfaces sensors and actuators to the SCADA network.
Correct answer is: Remote Terminal Unit
Q.155 Which SCADA component provides real‑time control logic execution?
PLC
RTU
HMI
SCADA Server
Explanation - PLCs perform real‑time control in industrial processes.
Correct answer is: PLC
Q.156 What is a common feature of OPC-UA that enhances security?
Built‑in authentication
No encryption
Only supports IPv4
Requires proprietary hardware
Explanation - OPC‑UA provides authentication and encryption.
Correct answer is: Built‑in authentication
Q.157 Which of the following SCADA protocols can run over both TCP and UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transports.
Correct answer is: DNP3
Q.158 What is the main role of an RTU in a SCADA system?
Data acquisition from sensors
Control logic execution
User interface display
Data logging
Explanation - RTUs gather sensor data and send it to the SCADA master.
Correct answer is: Data acquisition from sensors
Q.159 Which SCADA protocol can be secured using TLS encryption?
Modbus TCP
OPC-UA
DNP3
BACnet/IP
Explanation - OPC‑UA can use TLS for secure communication.
Correct answer is: OPC-UA
Q.160 What is a primary benefit of a data historian in SCADA?
Real‑time process control
Long‑term data storage and analysis
Providing graphical displays
Device configuration
Explanation - Historians archive time‑series data for analysis.
Correct answer is: Long‑term data storage and analysis
Q.161 Which layer of the OSI model handles logical addressing and routing decisions?
Network
Transport
Data Link
Physical
Explanation - The Network layer handles IP addresses and routing.
Correct answer is: Network
Q.162 Which SCADA component is primarily used to provide a graphical interface for operators?
HMI
RTU
PLC
Data Historian
Explanation - HMIs display data and allow operator interaction.
Correct answer is: HMI
Q.163 What does SCADA stand for?
Supervisory Control And Data Acquisition
System Control And Data Analysis
Standard Control And Data Application
Supervised Control And Data Algorithm
Explanation - SCADA stands for Supervisory Control And Data Acquisition.
Correct answer is: Supervisory Control And Data Acquisition
Q.164 Which of the following is NOT a typical SCADA communication protocol?
Modbus
DNP3
OPC-UA
HTTP
Explanation - HTTP is a web protocol, not used for SCADA control.
Correct answer is: HTTP
Q.165 Which device is used for data acquisition in SCADA?
RTU
PLC
HMI
SCADA Server
Explanation - RTUs read sensor data and send it to the SCADA server.
Correct answer is: RTU
Q.166 Which of the following protocols can run over both TCP and UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transport layers.
Correct answer is: DNP3
Q.167 What is a key security measure for SCADA systems?
Using default passwords
Disabling firewalls
Implementing role‑based access control
Leaving all ports open
Explanation - RBAC restricts user permissions.
Correct answer is: Implementing role‑based access control
Q.168 Which protocol can be secured using TLS encryption?
Modbus TCP
OPC-UA
DNP3
BACnet/IP
Explanation - OPC‑UA supports TLS for encryption.
Correct answer is: OPC-UA
Q.169 What is a common use of a historian in SCADA?
Store long‑term data for trend analysis
Provide user interfaces
Control field devices
Monitor network traffic
Explanation - Historians archive time‑series data.
Correct answer is: Store long‑term data for trend analysis
Q.170 Which layer of the OSI model deals with end‑to‑end error recovery?
Transport
Data Link
Network
Physical
Explanation - Transport layer provides reliability and flow control.
Correct answer is: Transport
Q.171 What does RTU stand for?
Remote Terminal Unit
Real Time Unit
Rapid Transfer Unit
Redundant Terminal Unit
Explanation - RTU is a field device that interfaces with the SCADA network.
Correct answer is: Remote Terminal Unit
Q.172 Which SCADA protocol is widely used over Ethernet?
Modbus TCP
Modbus RTU
DNP3
OPC Classic
Explanation - Modbus TCP is common for Ethernet‑based SCADA.
Correct answer is: Modbus TCP
Q.173 Which SCADA component handles real‑time control logic?
PLC
RTU
HMI
SCADA Server
Explanation - PLCs execute control logic in real time.
Correct answer is: PLC
Q.174 Which SCADA protocol can operate over both TCP and UDP?
Modbus TCP
DNP3
OPC UA
BACnet/IP
Explanation - DNP3 supports both TCP and UDP transports.
Correct answer is: DNP3
Q.175 Which feature of OPC-UA enhances security?
Built‑in authentication
No encryption
Only supports IPv6
Requires proprietary hardware
Explanation - OPC‑UA supports authentication and encryption.
Correct answer is: Built‑in authentication
Q.176 What is the main purpose of a SCADA alarm system?
To notify operators of abnormal conditions
To provide user interfaces
To store long‑term data
To control field devices
Explanation - Alarms alert operators to process deviations.
Correct answer is: To notify operators of abnormal conditions
Q.177 Which SCADA protocol is commonly used for secure communication in critical infrastructure?
Modbus TCP
DNP3 Secure
OPC Classic
BACnet/IP
Explanation - DNP3 Secure adds authentication and encryption.
Correct answer is: DNP3 Secure
Q.178 What does the 'master' in a SCADA system do?
Collects data from field devices
Controls field devices directly
Provides graphical displays
Logs historical data
Explanation - The master aggregates data and issues control commands.
Correct answer is: Collects data from field devices