Application Layer Implementation in IACS and the Internet of Things – Module 15 Exam Answers

Application Layer Implementation in IACS and the Internet of Things – Module 15 Exam Answers

Understanding the application layer’s role in Industrial Automation and Control Systems (IACS) and the Internet of Things (IoT) is critical for managing data flow and ensuring interoperability among devices. In this module, students are tested on key concepts, including application protocols, data exchange processes, and security measures for safeguarding communication. The exam answers provided here are designed to help learners validate their knowledge, analyze technical scenarios, and prepare effectively for real-world challenges in implementing application layer solutions within IACS and IoT environment

1. What does the term “server” refer to in the context of computer networks?

• A specialized computer providing information or services to other hosts on the network.
• A security mechanism used to protect network resources from unauthorized access.
• A piece of hardware responsible for routing network traffic.
• A device used by individual users to gain access to the internet.

In computer networking, a server is a specialized computer or software application designed to provide data, services, or resources to other computers, known as clients, over a network.

Correct Answer:
A specialized computer providing information or services to other hosts on the network.

Detailed Explanation:
In the context of computer networks, a server refers to a specialized computer or software application that manages and delivers resources, data, or services to other computers, known as clients. Servers are fundamental components of network architecture, facilitating various functions such as file sharing, hosting websites, managing emails, or running applications.

Servers are designed to handle multiple requests from clients simultaneously and operate continuously to ensure uninterrupted service. For instance, a web server provides web pages to users via HTTP/HTTPS, while a file server allows clients to store and retrieve data across a network.

They differ from typical client devices in that servers often have robust hardware specifications, including higher processing power, large storage capacity, and redundant components to ensure reliability and performance. Additionally, servers are integral to centralized resource management in both small-scale and enterprise-level networks.

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2. What does a Uniform Resource Name (URN) primarily identify?

• The specific location of a resource on the internet.
• The protocol used to access a resource on the internet.
• The IP address and the required protocol of the server hosting the resource.
• The namespace of a resource without reference to the protocol.

A Uniform Resource Name (URN) is a persistent identifier uniquely identifying a resource by name in a particular namespace. Unlike Uniform Resource Locators (URLs), which include the protocol and specific location, it does not specify how to access the resource.

Correct Answer:
The namespace of a resource without reference to the protocol.

Detailed Explanation:
A Uniform Resource Name (URN) is a persistent identifier used to uniquely identify a resource by its name within a defined namespace, without any indication of how or where the resource can be accessed. Unlike a Uniform Resource Locator (URL), which provides a location and access method (e.g., HTTP, FTP), a URN serves as a stable, location-independent identifier.

For example:
URN: urn:isbn:978-3-16-148410-0
This URN identifies a book by its International Standard Book Number (ISBN) but does not specify where the book can be found or how to retrieve it.

URNs are a part of the broader Uniform Resource Identifier (URI) framework, which encompasses both URNs and URLs. They are commonly used in scenarios where resources need to be referenced in a persistent and protocol-agnostic manner.

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3. What does a Uniform Resource Locator (URL) primarily define?

• The specific namespace of a resource without reference to the protocol
• The programming language in which the resource is coded
• The encryption method used to secure communication with the resource
• The network location of a specific resource on the network

A Uniform Resource Locator (URL) specifies the address of a resource on the internet, including the protocol (e.g., HTTP, HTTPS) and the specific location (e.g., domain name, directory, file name).

Correct Answer:
The network location of a specific resource on the network.

Detailed Explanation:
A Uniform Resource Locator (URL) is a string of text that defines the network location of a specific resource on the internet, along with the protocol required to access it. It serves as the web address, directing clients to the exact location of a webpage, file, or service.

A URL typically includes:

1. Protocol (e.g., http, https, ftp) – Specifies how to access the resource.
2. Domain name or IP address – Identifies the server hosting the resource.
3. Path (e.g., directory or file name) – Indicates the specific resource’s location on the server.
4. Optional components – Such as query parameters or fragments for additional details.

For example:
https://www.example.com/folder/resource.html

• Protocol: https
• Domain name: www.example.com
• Path: /folder/resource.html

URLs are essential for locating resources in a structured, accessible manner, distinguishing them from Uniform Resource Names (URNs), which focus only on naming resources.

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4. Which internet service is considered one of the most commonly used?

• Social media sites
• Augmented reality applications
• Virtual reality experiences
• Online gaming

People widely use social media platforms like Facebook, Twitter, Instagram, and LinkedIn for communication, networking, and sharing content online.

Correct Answer:
Social media sites

Detailed Explanation:
Among internet services, social media sites are considered one of the most commonly used. Platforms like Facebook, Twitter, Instagram, LinkedIn, TikTok, and others play a significant role in modern communication, networking, and content sharing. These platforms allow individuals to connect with friends, family, and professional contacts, share media, participate in discussions, and stay informed about current events.

The widespread use of smartphones, internet access, and user-friendly interfaces has further contributed to the popularity of social media. Social media platforms are used not only for personal interactions but also for business marketing, brand promotion, news dissemination, and community building, making them integral to the digital landscape.

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5. When a web client receives the IP address of a web server and wants to request web services, which port does the client browser typically use?

• Port 80
• Port 22
• Port 8080
• Port 443

When a web client receives the IP address of a web server, the client browser typically uses port 80 to request web services.

Correct Answer:
Port 80

Detailed Explanation:
When a web client (e.g., a browser) communicates with a web server to request web services, it typically uses port 80 for HTTP (HyperText Transfer Protocol) traffic. Port 80 is the default port assigned for unencrypted web traffic, making it standard for basic web communications.

If the connection requires secure communication, such as using HTTPS (HTTP Secure), the client will use port 443 instead. Port 443 ensures data encryption using SSL/TLS protocols for secure data transfer.

Here’s a breakdown of the options:

• Port 80: Default for HTTP (non-secure web traffic).
• Port 22: Used for SSH (Secure Shell), not for web services.
• Port 8080: Often used for proxy servers or alternate HTTP services.
• Port 443: Used for HTTPS (secure web traffic).

By default, web browsers use port 80 unless the URL specifies HTTPS, which directs the request to port 443.

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6. What is the primary function of HyperText Markup Language (HTML) coding in web development?

• managing server-side operations
• defining the structure and formatting of web pages, including graphics and fonts
• providing interactivity to web pages
• handling database connections, responds to client requests and controls data manipulation

HTML (HyperText Markup Language) is used to structure content and instruct web browsers on displaying web pages, including formatting, layout, and specifying graphics and fonts.

Correct Answer:
Defining the structure and formatting of web pages, including graphics and fonts

Detailed Explanation:
HyperText Markup Language (HTML) is the foundational language used in web development to define the structure, content, and layout of web pages. It serves as the backbone for creating and organizing elements such as text, headings, images, tables, and links, ensuring that web browsers can interpret and display them properly.

HTML’s primary role is structural, not interactive or functional like other languages (e.g., JavaScript or PHP). It uses tags and attributes to format and arrange page elements, such as:

• <h1> to <h6> for headings
• <p> for paragraphs
• <img> for images
• <a> for hyperlinks

By defining the appearance and arrangement of web content, HTML ensures a consistent and user-friendly browsing experience. For interactivity or dynamic content, technologies like JavaScript, CSS, and server-side scripting languages are combined with HTML.

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7. What is a characteristic of the HTTP protocol?

• HTTP is a secure protocol, making it difficult for unauthorized users to intercept data.
• HTTP encrypts all transmitted data.
• HTTP is not secure, as other users could easily intercept data transmitted over the network.
• HTTP is primarily used to transmit sensitive financial information.

The HTTP protocol is not a secure protocol; information could easily be intercepted by other users as data is sent over the network.

Correct Answer:
HTTP is not secure, as other users could easily intercept data transmitted over the network.

Detailed Explanation:
HTTP (HyperText Transfer Protocol) is a standard protocol used for transmitting data between a web browser (client) and a web server. However, it is not inherently secure because it transmits data in plain text. This means that any information sent via HTTP, such as form submissions or login credentials, can potentially be intercepted by unauthorized users or malicious entities using techniques like packet sniffing.

Key characteristics of HTTP:

• It is stateless, meaning each request from a client to a server is independent of previous requests.
• Data transmitted using HTTP is unencrypted, making it vulnerable to interception.

To address this security issue, HTTPS (HTTP Secure) was developed. HTTPS adds encryption using SSL/TLS protocols, ensuring that data transmitted between the client and server is protected from unauthorized access and tampering.

In summary, while HTTP is widely used for non-sensitive web communication, HTTPS is the preferred protocol for transmitting sensitive information like financial data or personal credentials.

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8. What makes it possible for web servers and web clients from different manufacturers to work together seamlessly?

• The use of closed-source software solutions.
• The implementation of complex encryption algorithms.
• The HTTP protocol and HTML standards.
• The use of proprietary protocols and standards.

The HTTP protocol (HyperText Transfer Protocol) and HTML (HyperText Markup Language) are open standards widely adopted across various web servers and web clients. These standards facilitate interoperability, allowing systems from different manufacturers to communicate and exchange information seamlessly.

Correct Answer:
The HTTP protocol and HTML standards.

Detailed Explanation:
The interoperability of web servers and web clients from different manufacturers is made possible by the HTTP protocol (HyperText Transfer Protocol) and HTML (HyperText Markup Language) standards. These are open, universally adopted standards that define how data is transmitted and presented on the web.

• HTTP Protocol: Specifies the rules for communication between a web client (browser) and a web server. It ensures that requests and responses follow a consistent structure, enabling seamless data exchange regardless of the software or hardware used.
• HTML Standards: Define the structure, format, and display of web content. Web browsers interpret HTML documents uniformly, ensuring compatibility across different platforms and devices.

By adhering to these open standards, manufacturers and developers ensure that their products work harmoniously in a heterogeneous environment, facilitating a consistent and user-friendly web experience. This universality is the foundation of the World Wide Web’s success.

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9. What were two common features of early computer systems before the advent of desktop computers with graphical interfaces? (Choose two.)

• use of text-based systems
• adoption of virtual reality technology
• development of complex graphical user interfaces (GUIs)
• utilization of display terminals connected to a central computer
• implementation of touchscreens for user interaction

Long before desktop computers with sophisticated graphical interfaces existed, people used text-based systems, often displaying terminals physically attached to a central computer.

Correct Answers:

• Use of text-based systems
• Utilization of display terminals connected to a central computer

Detailed Explanation:
Before the advent of modern desktop computers with graphical user interfaces (GUIs), early computer systems commonly featured the following:

• Text-Based Systems:
  • Early systems relied on text commands for interaction, using command-line interfaces (CLI) instead of graphical interfaces. Users entered commands to perform tasks, and output was displayed as text on the screen. Examples include operating systems like MS-DOS and Unix.
• Display Terminals Connected to a Central Computer:
  • Computing resources were centralized, and users accessed them via terminals (dumb terminals or teletype machines) connected to a mainframe or minicomputer. These terminals were primarily input/output devices with no processing power of their own.

At that time, complex GUIs, virtual reality technologies, and touchscreens were either non-existent or not practical for widespread use due to hardware and software limitations. These features became prevalent much later with the development of more advanced computing technologies.

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10. What is a connection using Telnet commonly called?

• a network emulation session
• a simulated terminal session
• a virtual terminal (vty) session
• an encrypted virtual connection

When using Telnet, the connection between the client and the server is often called a virtual terminal (vty) session or connection.

Correct Answer:
A virtual terminal (vty) session

Detailed Explanation:
When using Telnet, the connection established between a client and a server is commonly referred to as a virtual terminal (vty) session. Telnet allows users to remotely access and manage devices or servers over a network by simulating a terminal session. The term vty (virtual terminal) refers to the logical interface used for such remote connections.

Key characteristics of Telnet and vty sessions:

• Telnet operates using plain text, meaning data transmitted during the session (including credentials) is not encrypted, making it insecure for sensitive communications.
• Vty sessions provide a way to interact with the remote device’s command-line interface (CLI).
• While Telnet is often replaced by secure alternatives like SSH (Secure Shell), the concept of vty sessions remains integral to network device management.

In modern practice, Telnet is discouraged in favor of encrypted protocols like SSH for better security.

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11. In which two ways does Telnet provide access to a server’s command line interface (CLI)? (Choose two.)

• by providing graphical user interface (GUI) access to the server
• by establishing a direct physical connection to the server hardware
• by creating a virtual device that simulates a terminal session
• by enabling the execution of commands remotely over a network connection
• by encrypting the communication between the client and the server

Telnet uses software to create a virtual device that provides the same features as a terminal session and accesses the server’s command line interface (CLI).

Correct Answers:

• By creating a virtual device that simulates a terminal session
• By enabling the execution of commands remotely over a network connection

Detailed Explanation:
Telnet provides access to a server’s Command Line Interface (CLI) in the following ways:

• Creating a Virtual Device that Simulates a Terminal Session:
  • Telnet establishes a virtual terminal (vty) session, allowing users to interact with the server as though they were directly connected via a physical terminal. This simulation enables remote command-line access and control.
• Enabling the Execution of Commands Remotely Over a Network Connection:
  • Telnet allows users to send commands and receive responses from the server remotely. This makes it possible to manage and configure devices or servers without being physically present.

Note:
Telnet does not provide a graphical user interface (GUI) or encrypt communication. Because Telnet transmits data, including login credentials, in plain text, it is considered insecure and is often replaced by SSH for encrypted and secure remote access.

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12. Which protocol is recommended for secure remote access to network devices instead of Telnet?

• POP3 (Post Office Protocol version 3)
• SNMP (Simple Network Management Protocol)
• SSH (Secure Shell)
• FTP (File Transfer Protocol)

SSH is recommended for secure remote access to network devices instead of Telnet due to its ability to encrypt data transmitted over the network, providing higher security.

Correct Answer:
SSH (Secure Shell)

Detailed Explanation:
SSH (Secure Shell) is the recommended protocol for secure remote access to network devices. Unlike Telnet, which transmits data in plain text, SSH provides encryption, ensuring that all data, including login credentials, is securely transmitted over the network. This makes SSH a much safer option for managing and configuring devices remotely.

Why SSH is preferred:

• Data Encryption: Protects transmitted data from being intercepted or tampered with by unauthorized users.
• Authentication: Supports strong authentication methods, including password-based and key-based authentication.
• Integrity: Ensures the integrity of data during transmission, preventing man-in-the-middle attacks.

Other Options:

• POP3 (Post Office Protocol version 3): Used for retrieving emails, not for remote access.
• SNMP (Simple Network Management Protocol): Used for monitoring and managing network devices, not for CLI access.
• FTP (File Transfer Protocol): Used for file transfers, not for remote device access.

For secure and encrypted remote access, SSH is the industry standard.

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13. What capability does an established Telnet connection provide to users?

• graphical user interface (GUI) access to the server
• encrypted communication with the server for enhanced security
• ability to perform any authorized command line function on the server
• access to all functions on the server

Once a Telnet connection is established, users can execute commands and perform functions on the server as if they were directly using a command line session on the server itself.

Correct Answer:
Ability to perform any authorized command line function on the server

Detailed Explanation:
An established Telnet connection allows users to remotely access the server’s command line interface (CLI) and execute any authorized commands or perform functions for which they have the necessary permissions. This makes it possible to manage and configure the server or device remotely, similar to being physically present at the machine.

Key Features of Telnet:

• Command Execution: Users can perform tasks such as system configuration, file management, and process monitoring based on their access level.
• Plain Text Communication: Telnet does not encrypt data, which makes it unsuitable for transmitting sensitive information.

Limitations:

• Access Restrictions: Users can only execute commands or access areas permitted by their credentials.
• Lack of Security: Unlike SSH, Telnet does not provide encryption, making it vulnerable to interception and unauthorized access.

While Telnet provides functionality to perform authorized tasks, access to “all functions on the server” is not automatically granted unless explicitly configured. Security protocols and access controls typically restrict unauthorized actions.

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14. Which protocol provides stronger authentication and encrypted data transportation for virtual terminal sessions?

• SNMP (Simple Network Management Protocol)
• Telnet
• FTP (File Transfer Protocol)
• SSH (Secure Shell)

SSH provides stronger authentication and supports encrypted session data transportation, making it suitable for secure remote login and network services.

Correct Answer:
SSH (Secure Shell)

Detailed Explanation:
SSH (Secure Shell) is a protocol designed to provide secure authentication and encrypted communication for virtual terminal sessions and other network services. It is widely used for secure remote access to servers and network devices, replacing insecure protocols like Telnet.

Key Features of SSH:

• Stronger Authentication:
  • Supports robust authentication mechanisms, including password-based authentication and public/private key pairs.
• Encrypted Data Transportation:
  • Encrypts all data transmitted between the client and server, protecting it from eavesdropping or interception.
• Integrity Assurance:
  • Ensures the transmitted data is not altered during transmission.

Why Other Options Are Less Secure:

• SNMP: Used for network management and monitoring, not for secure terminal sessions.
• Telnet: Provides no encryption, transmitting data in plain text, making it vulnerable to interception.
• FTP: Used for transferring files but does not inherently provide strong encryption or authentication.

SSH is the industry standard for secure remote access due to its combination of authentication, encryption, and data integrity.

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15. Which two protocols would a router use to communicate with a central AAA server to authenticate a user? (Choose two.)

• RADIUS
• IMAP
• Telnet
• Secure Shell (SSH)
• TACACS+
• HTTPS