A broadband router is a networking device designed for home and small office (SOHO) environments. Its primary function is to share a single broadband internet connection among multiple computers. It integrates the capabilities of a router (to connect to the internet), a network switch (to connect local computers together via Ethernet cables), and often a wireless access point. This single device fulfills both requirements of connecting computers to each other on a local network and connecting that entire network to the internet.

A. Inter-provider border router: This router is used by Internet Service Providers (ISPs) to connect their network to other ISP networks, not for end-user local networking.

B. Subscriber edge router: This is typically the router on the ISP's side of the network that connects directly to the customer's premises equipment.

D. Core router: This is a high-capacity router that operates within the backbone of a large network, forwarding traffic between major network segments, not connecting end-user devices.

1. Kurose

J. F.

& Ross

K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 1

Section 1.3

the text describes the typical home network architecture where a "home router" (a common broadband router) connects internal devices to each other and to the ISP's modem for internet access.

2. Cisco. (n.d.). What Is a Router?. Cisco.com. This official vendor documentation distinguishes between different router types

describing small business or home routers (i.e.

broadband routers) as devices that connect multiple devices to the internet

contrasting them with high-performance service provider core and edge routers.

3. Comer

D. E. (2015). Computer Networks and Internets (6th ed.). Pearson. Chapter 19

"Internet Routing

" discusses the hierarchy of routers. It implicitly differentiates between the large

powerful routers forming the internet's core and the small routers used at the edge to connect a site or home to an ISP. The device in the question is an edge device

specifically a broadband router.

The scenario describes implementing encryption standards for a network protocol. The primary purpose of encryption is to convert data into a coded format (ciphertext) to prevent unauthorized access. This directly addresses the principle of Confidentiality, which is concerned with preventing the unauthorized disclosure of information. By ensuring network protocols meet encryption standards, the company is protecting the secrecy of the data as it travels across the network, making it unreadable to anyone without the proper decryption key.

A. Integrity: Integrity ensures data is not altered without authorization. While some cryptographic methods provide integrity, its primary tool is hashing, not just encryption.

B. Consistency: Consistency is a principle related to database systems (ACID properties) and is not a component of the information security CIA triad.

C. Availability: Availability ensures that systems and data are accessible when needed. Encryption does not provide availability; lost keys can actually prevent access.

1. National Institute of Standards and Technology (NIST). (2020). Security and Privacy Controls for Information Systems and Organizations (NIST Special Publication 800-53

Revision 5). U.S. Department of Commerce. In Appendix D

"Glossary

" confidentiality is defined as "Preserving authorized restrictions on information access and disclosure..." Encryption is a primary mechanism for achieving this. (See page 218).

2. Saltzer

J. H.

& Schroeder

M. D. (1975). The Protection of Information in Computer Systems. Proceedings of the IEEE

63(9)

1278–1308. This foundational paper outlines security principles

where confidentiality is described as the prevention of unauthorized disclosure of information

a goal directly served by encryption. (See Section I.A.1

page 1279).

3. Massachusetts Institute of Technology (MIT) OpenCourseWare. (2018). 6.033 Computer System Engineering

Spring 2018. Lecture 19: Security. The lecture notes explicitly define confidentiality as preventing unauthorized disclosure of information and list encryption as the primary mechanism to achieve it. (See slide 4

"Security goals").

The dig (Domain Information Groper) command is a standard and powerful command-line tool in Linux used for interrogating Domain Name System (DNS) servers. Its primary purpose is to perform DNS lookups and return detailed information from the name server, including A records, MX records, and other DNS data. For an administrator troubleshooting DNS resolution, dig is the most appropriate and direct tool as it provides comprehensive output specifically tailored for diagnosing DNS issues.

A. traceroute: This command is used to trace the network path (route) packets take to a destination, not to test DNS resolution directly.

B. netstat: This command displays network connections, routing tables, and interface statistics; it does not perform DNS queries for troubleshooting.

D. ifconfig: This command is used to view and configure network interface parameters, such as IP addresses, and is not used for DNS lookups.

1. University Courseware:

MIT OpenCourseWare

6.033 Computer System Engineering

Spring 2018

Recitation 10: Naming. The notes explicitly introduce dig as the tool for querying the DNS. "To query the DNS

we can use the dig command." (Section 2

Paragraph 1).

Available at: https://ocw.mit.edu/courses/6-033-computer-system-engineering-spring-2018/resources/mit6033s18rec10/

2. Official Vendor Documentation:

Red Hat Enterprise Linux 8 Documentation

Configuring and managing networking

Chapter 36. Analyzing network traffic. The documentation lists dig as a primary utility for DNS troubleshooting. "The dig utility sends a DNS query to a name server and displays the result." (Section 36.2.1. Querying DNS records using dig).

Available at: https://access.redhat.com/documentation/en-us/redhatenterpriselinux/8/html/configuringandmanagingnetworking/analyzing-network-trafficconfiguring-and-managing-networking

3. Official Linux Documentation (Man Page):

The Linux man-pages project

dig(1). The official manual page describes the tool's function. "dig (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried." (NAME section).

Available at: https://man7.org/linux/man-pages/man1/dig.1.html

The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet Protocol (IP) suite. It operates at the Network Layer (Layer 3) of the OSI model. ICMP is not used for exchanging data between end systems but rather for sending error messages and operational information indicating, for example, that a requested service is not available or that a host or router could not be reached. Because ICMP messages are encapsulated directly within IP datagrams and are integral to the function of IP (e.g., path discovery, error reporting), it is fundamentally a Network Layer protocol.

A. Transport: The Transport Layer (Layer 4) is responsible for end-to-end communication using protocols like TCP and UDP, not for network-level error reporting.

B. Session: The Session Layer (Layer 5) establishes, manages, and terminates connections between applications, a function unrelated to ICMP's network control purpose.

D. Application: The Application Layer (Layer 7) provides network services directly to user applications (e.g., HTTP, FTP). ICMP supports the underlying network, not the applications themselves.

---

1. Postel

J. (1981). RFC 792: Internet Control Message Protocol. Internet Engineering Task Force (IETF).

Section: "Introduction

" Paragraph 2.

Content: "ICMP

uses the basic support of IP as if it were a higher level protocol

however

ICMP is actually an integral part of IP

and must be implemented by every IP module." This establishes ICMP as an essential component of IP

which resides at the Network Layer.

Link: https://doi.org/10.17487/RFC0792

2. Cisco Systems

Inc. (2001). Internetworking Technology Handbook: Internet Protocols.

Section: "Chapter 45: Internet Protocols

" Figure 45-1 "Internet Protocol Suite and the OSI Reference Model."

Content: The official diagram in this vendor documentation explicitly maps ICMP alongside IP in the Network Layer of the OSI model.

3. Kurose

J. F.

& Ross

K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson.

Section: Chapter 4

"The Network Layer: Data Plane

" Section 4.4.1 "The Internet Control Message Protocol (ICMP)."

Content: The text states

"ICMP is often considered part of IP

but architecturally it lies just above IP

as ICMP messages are carried inside IP datagrams... ICMP messages are used by hosts and routers to communicate network-layer information to each other." This places it firmly within the Network Layer's scope.

The scenario describes the implementation of role-based permissions, a core mechanism of access control. This directly addresses the concept of authorization. Authorization is the process that determines what permissions an authenticated entity (a user or system) has for accessing resources or performing actions. By assigning permissions based on job roles, the company is explicitly defining and enforcing what each user is allowed to do, which is the essence of authorization. This practice enforces the principle of least privilege to mitigate risks like insider attacks.

A. Authentication: This is the process of verifying a user's identity (e.g., with a password or biometric scan), not determining their access rights.

B. Accounting: This refers to the tracking and logging of user activities for auditing purposes, which occurs after access has been granted and used.

C. Availability: This is a goal of security (part of the CIA triad) that ensures systems and data are accessible to authorized users, not the process of granting permissions.

---

1. National Institute of Standards and Technology (NIST). (2006). Assessment of Access Control Systems. NISTIR 7316.

Page 10

Section 2.2.2: Defines Authorization as "The process of determining

by evaluating applicable access control information

whether a subject is allowed to have the specified types of access to a particular resource... The authorization process occurs after the authentication process." This directly supports that assigning permissions is an act of authorization.

2. National Institute of Standards and Technology (NIST). (2020). Security and Privacy Controls for Information Systems and Organizations. NIST Special Publication 800-53

Revision 5.

Page 101

Section AC-2 (Account Management): This control family discusses assigning access rights (privileges) based on roles and the principle of least privilege

which are fundamental to authorization. The document states

"The organization: a. Defines and documents the rights and privileges of each assigned account role."

3. Saltzer

J. H.

& Schroeder

M. D. (1975). The Protection of Information in Computer Systems. Proceedings of the IEEE

63(9)

1278–1308.

Section I.A.3

Page 1281: This foundational academic paper distinguishes between authentication and authorization. It explains that after authentication confirms a user's identity

the system must have a way to "authorize access

" which involves consulting a list of authorizations (permissions) for that user. This establishes the academic basis for the distinction. (DOI: https://doi.org/10.1109/PROC.1975.9939)

4. Massachusetts Institute of Technology (MIT) OpenCourseWare. (2019). 6.858 Computer Systems Security

Fall 2014.

Lecture 2: Control Hijacking

Slide 5: The lecture slides clearly define the security model components: "Authentication: who is the user? Authorization: is user X allowed to do operation Y? (access control)." This university source explicitly equates authorization with access control and the act of determining allowed operations.