ISA-IEC-62443 ISA/IEC 62443 Cybersecurity Fundamentals Specialist Free Practice Exam Questions (2025 Updated)

The primary responsibility of the network layer of the Open Systems Interconnection (OSI) model is to forward packets, including routing through intermediate routers. The network layer is the third layer from the bottom of the OSI model, and it is responsible for maintaining the quality of the data and passing and transmitting it from its source to its destination. The network layer also assigns logical addresses to devices, such as IP addresses, and uses various routing algorithms to determine the best path for the packets to travel. The network layer operates on packets, which are units of data that contain the source and destination addresses, as well as the payload. The network layer forwards packets from one node to another, using routers to switch packets between different networks. The network layer also handles host-to-host delivery, which means that it ensures that the packets reach the correct destination host.

The other choices are not correct because:

B. Gives transparent transfer of data between end users. This is the responsibility of the transport layer, which is the fourth layer from the bottom of the OSI model. The transport layer provides reliable and error-free data transfer between end users, using protocols such as TCP and UDP. The transport layer operates on segments, which are units of data that contain the source and destination port numbers, as well as the payload. The transport layer also handles flow control, congestion control, and multiplexing.

C. Provides the rules for framing, converting electrical signals to data. This is the responsibility of the data link layer, which is the second layer from the bottom of the OSI model. The data link layer provides the means for transferring data between adjacent nodes on a network, using protocols such as Ethernet and WiFi. The data link layer operates on frames, which are units of data that contain the source and destination MAC addresses, as well as the payload. The data link layer also handles error detection, error correction, and media access control.

D. Handles the physics of getting a message from one device to another. This is the responsibility of the physical layer, which is the lowest layer of the OSI model. The physical layer provides the means for transmitting bits over a physical medium, such as copper wire, fiber optic cable, or radio waves. The physical layer operates on bits, which are the smallest units of data that can be either 0 or 1. The physical layer also handles modulation, demodulation, encoding, decoding, and synchronization.

The Open Systems Interconnection (OSI) model is a framework that describes the functions of a networking system. The OSI model categorizes the computing functions of the different network components, outlining the rules and requirement needed to support the interoperability of the software and hardware that make up the network1.

The OSI model consists of seven abstraction layers arranged in a top-down order: Physical, Data Link, Network, Transport, Session, Presentation, and Application. The Transport layer is the fourth layer in the OSI model, and it is responsible for ensuring reliable and efficient data transfer between the Network layer and the Session layer2. The Transport layer uses protocols such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) to provide end-to-end communication services, such as error detection and correction, flow control, congestion control, and segmentation2.

The image that you sent shows a 3D representation of the OSI model, with the layers stacked on top of each other. The missing layer is the Transport layer, which is represented by a pink box with a white arrow pointing to it. The arrow is labeled “TCP, UDP”.

1: What is the OSI Model? 7 Network Layers Explained | Fortinet 2: What is OSI Model | 7 Layers Explained - GeeksforGeeks

ISA/IEC 62443-2-1 emphasizes the importance of the ongoing evaluation of organizational responsibilities and training as part of continuous improvement within the CSMS. Periodic assessment ensures that personnel remain aware of their roles, are adequately trained, and that the program adapts to changes in the environment, technology, or threat landscape. The standard discourages keeping responsibilities static or expanding without control; instead, it advocates for regular reviews and updates.

Foundational Requirement 1 (FR 1) is “Identification and Authentication Control” (IAC). Its primary purpose is to control access to selected devices and systems by ensuring that only authorized individuals or entities can access them. This involves authentication mechanisms, unique IDs, and credential management. It does not primarily deal with data confidentiality or incident response, but with controlling device access.

 IPSec is a commonly used protocol for managing secure data transmission over a VPN. IPSec stands for Internet Protocol Security and it is a set of standards that define how to encrypt and authenticate data packets that travel between two or more devices over an IP network. IPSec can operate in two modes: transport mode and tunnel mode. In transport mode, IPSec only encrypts the payload of the IP packet, leaving the header intact. In tunnel mode, IPSec encrypts the entire IP packet and encapsulates it in a new IP header. Tunnel mode is more secure and more suitable for VPNs, as it can protect the original source and destination addresses of the IP packet from eavesdropping or spoofing. IPSec uses two main protocols to provide security services: Authentication Header (AH) and Encapsulating Security Payload (ESP). AH provides data integrity and source authentication, but not confidentiality. ESP provides data integrity, source authentication, and confidentiality. IPSec also uses two protocols to establish and manage security associations (SAs), which are the parameters and keys used for encryption and authentication: Internet Key Exchange (IKE) and Internet Security Association and Key Management Protocol (ISAKMP). IKE is a protocol that negotiates and exchanges cryptographic keys between two devices. ISAKMP is a protocol that defines the format and structure of the messages used for key exchange and SA management.

 According to the ISA/IEC 62443-2-4 standard, a training and security awareness program should include all personnel who have access to the industrial automation and control system (IACS) or who are involved in its operation, maintenance, or management. This includes vendors and suppliers, employees, temporary staff, contractors, and visitors. The purpose of the program is to ensure that all personnel are aware of the security risks and policies related to the IACS, and that they have the necessary skills and knowledge to perform their roles in a secure manner. The program should also cover the roles and responsibilities of different personnel, the reporting procedures for security incidents, and the best practices for security hygiene. References:

ISA/IEC 62443-2-4:2015 - Security for industrial automation and control systems - Part 2-4: Security program requirements for IACS service providers1

ISA/IEC 62443 Cybersecurity Fundamentals Specialist Training Course2

The asset model is used in ISA/IEC 62443 to represent and describe the relationships and dependencies between different assets in an IACS environment. This model helps organizations identify and document assets, their interconnections, and their significance for operational and cybersecurity purposes. The zone model builds upon the asset model for segmentation, but the asset model itself establishes the foundational relationships.

The “Maintain” phase is the fourth phase of the IACS Cybersecurity Lifecycle described in ISA/IEC 62443-2-1. A key activity in this phase is managing changes (also known as “change management”). This activity ensures that any modifications to the IACS environment (hardware, software, processes, etc.) are evaluated for cybersecurity impact, and proper controls are implemented to maintain the intended security posture. While risk assessment is typically done in the Assess phase, and allocating assets and designing countermeasures belong to earlier phases, managing changes is essential for ensuring ongoing compliance and effectiveness of cybersecurity controls over time.

Datagram Transport Layer Security (DTLS) and Secure Sockets Layer (SSL) are both commonly used protocols for managing secure data transmission on the Internet. DTLS is a variant of SSL that is designed to work over datagram protocols such as UDP, which are used for real-time applications such as voice and video. SSL is a protocol that provides encryption, authentication, and integrity for data transmitted over TCP, which is used for reliable and ordered delivery of data. Both DTLS and SSL use certificates and asymmetric cryptography to establish a secure session between the communicating parties, and then use symmetric cryptography to encrypt the data exchanged. DTLS and SSL are widely used in web browsers, email clients, VPNs, and other applications that require secure communication over the Internet. References:

ISA/IEC 62443 Standards to Secure Your Industrial Control System, Module 3: Introduction to Cryptography, pages 3-5 to 3-7

Using the ISA/IEC 62443 Standards to Secure Your Control System, Chapter 6: Securing Communications, pages 125-126

Packet filter firewalls, as defined by ISA/IEC 62443 standards on cybersecurity, primarily examine the source, destination, and ports in the header of each packet. This type of firewall does not inspect the packet content deeply (such as its structure or sequence) or maintain awareness of the relationships between packets in a session. Instead, it operates at a more superficial level, filtering packets based solely on IP addresses and TCP/UDP ports. This approach allows packet filter firewalls to quickly process and either accept or block packets based on these predefined criteria without delving into the complexities of session management or the content of the packets up to the application layer.

The reference model provides the overall conceptual basis for designing an appropriate security program. The ISA/IEC 62443-1-1 standard introduces the reference model to explain the structure, concepts, and relationships within an industrial automation and control system (IACS). It establishes the foundation for applying zones and conduits and for understanding security levels and how assets interact. This model is the cornerstone for implementing other architectural and technical security controls.

 A vulnerability scanner is a tool that scans a network or a system for known vulnerabilities, such as misconfigurations, outdated software, or weak passwords. A vulnerability scanner can provide valuable information for improving the security posture of a system, but it can also cause serious disruption of a control network if used on a live system. This is because a vulnerability scanner may generate a large amount of network traffic, consume system resources, trigger alarms, or even crash devices by exploiting vulnerabilities. Therefore, a vulnerability scanner should not be used on a live system without proper authorization and precautions. A vulnerability scanner should only be used on a test or isolated network, or during a scheduled maintenance window with minimal impact on the system operation. References: ISA/IEC 62443 Standards to Secure Your Industrial Control System, Module 5: Assessing the Current Security Level, Slide 25.

 Periodic audits are an essential part of the ISA/IEC 62443 cybersecurity standards, as they help to verify the effectiveness and compliance of the security program. According to the ISA/IEC 62443-2-1 standard, periodic audits should be conducted to evaluate the following aspects1:

The security policies and procedures are consistent with the security requirements and objectives of the organization

The security policies and procedures are implemented and enforced in accordance with the security program

The security policies and procedures are reviewed and updated regularly to reflect changes in the threat landscape, the IACS environment, and the business needs

The security performance indicators and metrics are measured and reported to the relevant stakeholders

The security incidents and vulnerabilities are identified, analyzed, and resolved in a timely manner

The security awareness and training programs are effective and aligned with the security roles and responsibilities of the personnel

The security audits and assessments are conducted by qualified and independent auditors

The security audit and assessment results are documented and communicated to the appropriate parties

The security audit and assessment findings and recommendations are addressed and implemented in a prioritized and systematic way Periodic audits are not only a means to meet regulations or adhere to a schedule, but also a way to validate that the security policies and procedures are performing as intended and achieving the desired security outcomes. Periodic audits also help to identify gaps and weaknesses in the security program and provide opportunities for improvement and enhancement. References: Periodic audits are an essential part of the ISA/IEC 62443 cybersecurity standards, as they help to verify the effectiveness and compliance of the security program. According to the ISA/IEC 62443-2-1 standard, periodic audits should be conducted to evaluate the following aspects1:

The security policies and procedures are consistent with the security requirements and objectives of the organization

The security policies and procedures are implemented and enforced in accordance with the security program

The security policies and procedures are reviewed and updated regularly to reflect changes in the threat landscape, the IACS environment, and the business needs

The security performance indicators and metrics are measured and reported to the relevant stakeholders

The security incidents and vulnerabilities are identified, analyzed, and resolved in a timely manner

The security awareness and training programs are effective and aligned with the security roles and responsibilities of the personnel

The security audits and assessments are conducted by qualified and independent auditors

The security audit and assessment results are documented and communicated to the appropriate parties

The security audit and assessment findings and recommendations are addressed and implemented in a prioritized and systematic way Periodic audits are not only a means to meet regulations or adhere to a schedule, but also a way to validate that the security policies and procedures are performing as intended and achieving the desired security outcomes. Periodic audits also help to identify gaps and weaknesses in the security program and provide opportunities for improvement and enhancement. References:

The “Addressing Risk” CSMS category consists of three element groups: Security Policy, Organization and Awareness; Selected Security Countermeasures; and Implementation of Security Program1. These element groups cover the aspects of defining the security objectives, roles and responsibilities, policies and procedures, awareness and training, security countermeasures selection and implementation, and security program execution and maintenance1. The “Addressing Risk” CSMS category aims to reduce the security risk to an acceptable level by applying appropriate security measures to the system under consideration (SuC)1. References: 1: ISA/IEC 62443-2-1: Security for industrial automation and control systems: Establishing an industrial automation and control systems security program

The four documents classified under the General category of ISA/IEC 62443 are:

Part 1-1: Terminology, concepts, and models

Part 1-2: Master glossary of terms and definitions

Part 1-3: System security conformance metrics

In the context of ISA/IEC 62443, maintenance activities by IACS Maintenance Service Providers generally begin after the solution (such as a control system or automation project) is handed over to the asset owner. This marks the transition from project (installation and commissioning) to operational maintenance, which includes patching, updating, and other support activities as part of the system lifecycle.

The Risk Analysis category contains background information that is used to identify and assess the risks associated with the cyber-physical system (CPS) under consideration. This information includes the system description, the threat model, the vulnerability analysis, the risk assessment method, and the risk acceptance criteria. The Risk Analysis category is used as an input for many other elements in the CSMS, such as the Risk ID, Risk Reduction, Risk Acceptance, and Risk Monitoring elements. The Risk Analysis category provides the basis for the risk management process and helps to ensure a consistent and systematic approach to cybersecurity in the CPS. References:

Using the ISA/IEC 62443 Standards to Secure Your Control System, page 13

[ISA/IEC 62443 Cybersecurity Fundamentals Specialist Study Guide], page 34

In cybersecurity, a demilitarized zone (DMZ) refers to a physical or logical subnetwork that contains and exposes an organization's external-facing services to an untrusted network, typically the internet. The main characteristic of a DMZ is that it acts as a buffer zone between the public internet and the private network. This allows for internet access through the firewall while keeping the internal network secure. Internet-facing servers are placed in the DMZ so that they are separated from the rest of the internal network. By doing so, if a server in the DMZ is compromised, the attacker would not have direct access to the internal network. This architecture is commonly used to host services such as web servers, mail servers, and FTP servers. Choice C is the most closely associated with the deployment of a DMZ as it allows for regulated and monitored internet access through a firewall.

According to the ISA/IEC 62443 standard, the connections between security zones are called conduits. A conduit is defined as a logical or physical grouping of communication channels connecting two or more zones that share common security requirements. A conduit can be used to control and monitor the data flow between zones, and to apply security measures such as encryption, authentication, filtering, or logging. A conduit can also be used to isolate zones from each other in case of a security breach or incident. A conduit can be implemented using various technologies, such as firewalls, routers, switches, cables, or wireless links. However, these technologies are not synonymous with conduits, as they are only components of a conduit. A firewall, for example, can be used to create multiple conduits between different zones, or to protect a single zone from external threats. Therefore, the other options (firewalls, tunnels, and pathways) are not correct names for the connections between security zones. References:

ISA/IEC 62443-3-2:2016 - Security for industrial automation and control systems - Part 3-2: Security risk assessment and system design1

ISA/IEC 62443-3-3:2013 - Security for industrial automation and control systems - Part 3-3: System security requirements and security levels2

Zones and Conduits | Tofino Industrial Security Solution3

Key Concepts of ISA/IEC 62443: Zones & Security Levels | Dragos4