Defense in Depth Assignment Help
A step-by-step guide for designing a layered network, drawing a Visio diagram, and writing a high-scoring 6–10 page paper on the CIA triad and security architecture.
Get Expert Help on This AssignmentWhat Is Defense in Depth?
Defense in Depth (DiD) is a cybersecurity strategy that places multiple independent layers of security controls across a network. The principle is simple: if one layer fails, the next layer stops the attack. No single control is considered sufficient. The concept originates from military strategy, where multiple defensive lines slow down and ultimately stop an advancing threat.
In a corporate network context, DiD translates to combining perimeter controls (firewalls, DMZs), internal segmentation (VLANs, subnets), access controls (authentication, role-based permissions), monitoring tools (IDS/IPS), encryption (VPNs, TLS), and physical security into a cohesive architecture. Each layer targets a different attack vector, which is why the approach is also described as layered security.
The National Institute of Standards and Technology (NIST) formally addresses this model in its security publications, particularly NIST SP 800-53 Rev. 5, which provides a comprehensive catalog of security controls organized by function — a directly citable source for your assignment.
Assignment Context: This guide addresses the two-part assignment in which you design a corporate network (one Chicago site + one remote site) using defense in depth, produce a Visio network diagram, and write a 6–10 page paper covering data flow, the CIA triad, and network isolation. It is not a finished paper — it is a structured guide to help you build your own.
Breaking Down the Assignment Requirements
Before you open Visio or type a single word, dissect what the assignment actually demands. Students lose marks by misreading the scope. Here is what each part requires:
| Section | Deliverable | Key Requirement |
|---|---|---|
| Part 1 | Network Diagram (Visio or Dia) | At least 4/5 of listed device types; defense in depth visible; credible sources cited |
| Part 2 | 6–10 Page Paper | Data flow from remote site; CIA triad explained; network isolation discussed; ≥4 academic sources synthesized |
| Both Parts | Source Citations | Every source on your reference page cited at least once in the text |
The assignment specifies two sites: a corporate site in Chicago (300 employees, all servers, 50 Mbps Internet) and a remote site 8 miles away (20 employees, needs full access to corporate resources, 3 Mbps Internet). Your diagram and paper must account for both sites, including how they connect to each other and to the Internet.
Common Mistake: Students draw one flat network with firewalls on the perimeter and call it “defense in depth.” That misses the point. The grader is looking for multiple distinct layers, each addressing a separate threat category — from perimeter to endpoint. Make those layers visible and label them.
Part 1 — How to Approach the Network Diagram
The diagram is the foundation. The paper explains what you drew, so a weak diagram leads to a weak paper. Think through the architecture before touching the drawing tool.
What “Defense in Depth in Mind” Means for Your Diagram
A defense in depth network diagram is not just a map of devices. It is a visual argument that security is layered. To communicate that visually, you need distinct zones — each separated by a control boundary. A common approach uses the following network zones:
Internet / Untrusted Zone
Represented as a cloud. This is where external traffic originates. No internal resources should be directly reachable from here without passing through at least one control.
DMZ (Demilitarized Zone)
A screened subnet sitting between two firewalls. Public-facing servers (web server, FTP server, mail server) belong here. If this zone is compromised, the attacker still cannot reach internal resources directly.
Internal Corporate Network
The main LAN behind the internal firewall. File servers, print servers, and internal workstations live here. Traffic between the DMZ and this zone is filtered.
Remote Site Network
The 20-employee site. Connected to the corporate site via a VPN tunnel over the Internet (3 Mbps). Traffic must traverse the VPN and corporate firewall before reaching internal resources.
Required Network Devices — Checklist
The assignment requires you to depict “at least four-fifths” of the listed device categories. Below is each category and how it fits into a defense in depth architecture:
- Routers: One at the Chicago site connecting to the Internet; one at the remote site connecting to its Internet link. Routers handle inter-network traffic and can enforce basic access control lists (ACLs).
- Switches: Layer 2/3 switches inside each site to connect end-user devices. VLANs on managed switches create logical network segments within the same physical infrastructure.
- Firewalls: At minimum, two at the corporate site — one facing the Internet (perimeter) and one separating the DMZ from the internal LAN. A third firewall at the remote site is reasonable. Stateful firewalls inspect traffic at the session level.
- VPN Concentrator / Gateway: Establishes the encrypted tunnel between the remote site and the Chicago corporate site. This is the mechanism allowing remote employees to access internal resources securely over a public Internet connection.
- Proxy Server: Sits between internal users and the Internet. Filters outbound web traffic, caches content, and enforces acceptable use policy. Useful for logging and inspection.
- IDS (Intrusion Detection System): Monitors traffic on key network segments and generates alerts when suspicious patterns are detected. Can be placed to monitor the DMZ, the internal LAN, or both. Note: an IDS monitors; it does not block (that is an IPS).
- Servers in the DMZ: Web server, FTP server, and mail server should be in the screened subnet. File and print servers should be on the internal network only.
- End-User Devices: Desktops at the corporate site and at the remote site. Laptops may appear as mobile endpoints.
Diagram Tip: Use Visio’s built-in Network shapes (Cisco or generic). Label every device. Draw zone boundaries using dashed rectangles with labels (“DMZ,” “Internal LAN,” “Remote Site”). Add a legend identifying what each symbol represents. Graders should not have to guess what a shape means.
Credible Sources to Cite in Your Diagram Notes
Yes, you need sources even in the diagram. Add a small “Notes/References” text box to your diagram and cite the sources that justify your design choices. Examples of citable justifications:
- Why a DMZ? Cite a source explaining screened subnets and dual-firewall architecture.
- Why a VPN for the remote site? Cite a source on secure remote access for branch offices.
- Why an IDS? Cite a source explaining intrusion detection as a layer of the defense in depth model.
The NIST SP 800-53 Rev. 5 control families SC (System and Communications Protection) and SI (System and Information Integrity) directly address network segmentation, boundary protection, and intrusion detection. These are credible, authoritative sources appropriate for an academic paper or diagram annotation.
Part 2 — How to Structure the 6–10 Page Paper
The paper is an explanation of your diagram supported by credible academic sources. It has three main analytical components: data flow, the CIA triad, and the argument for layered security through network isolation. Here is a workable structure:
Introduction (~0.5 pages)
State the purpose of the paper. Briefly describe the two-site network you designed and introduce the concept of defense in depth. End with a thesis statement that previews your analysis of data flow and the CIA triad. Keep this section tight — one paragraph is enough.
Network Overview (~0.5 pages)
Describe the two-site architecture at a high level. Identify the major zones (Internet, DMZ, Internal LAN, Remote Site), the key security controls at each boundary, and reference your diagram. This sets the context for the data flow section.
Data Flow Analysis (~2–3 pages)
This is the most detailed analytical section. Trace a specific data transaction from its origin at the remote site to its destination on the corporate network. Walk through every network boundary the data crosses and describe what security control it encounters at each point. This must be tied to cited sources. See the Data Flow section below for a detailed breakdown.
CIA Triad Analysis (~2–3 pages)
Explain all three elements of the CIA triad (Confidentiality, Integrity, Availability) and then connect each element to specific design decisions in your network. This section must cite academic sources and show how your architecture delivers each property. See the CIA Triad section below.
Network Isolation and Layered Security (~1–2 pages)
Explain the defense in depth model explicitly. Argue why network isolation — separating resources by function into distinct zones — produces better security outcomes than a flat network with a single perimeter control. Cite sources that support the argument for segmentation and layered controls.
Conclusion (~0.5 pages)
Summarize your main findings. Restate how the design achieves defense in depth and delivers the CIA triad properties. No new information in the conclusion.
Understanding the CIA Triad — and How to Apply It
The CIA triad is the foundational framework of information security. Your paper must explain all three elements and show how your network design addresses each one. Explaining the definitions without connecting them to your architecture will not earn full marks.
Confidentiality
Confidentiality means ensuring that data is accessible only to those authorized to access it. In your network, confidentiality is delivered by several mechanisms working together: the VPN encrypts data in transit between the remote site and Chicago so it cannot be intercepted on the public Internet; the firewall rules restrict which devices can communicate with the file server; VLANs limit broadcast domains so that a device on one VLAN cannot see traffic on another; and access controls on the file server itself require authentication before any data can be read.
When writing this section, explain how each control contributes to confidentiality, not just that it exists. Then cite a source that explains why encryption or network segmentation is effective for confidentiality protection.
Integrity
Integrity means ensuring that data has not been altered in an unauthorized or undetected way. In your network, integrity is supported by the IDS, which monitors for unusual traffic patterns that might indicate data tampering or man-in-the-middle activity; by the VPN, which uses cryptographic authentication to verify that data has not been modified in transit; and by access controls that prevent unauthorized users from writing to the file server.
A strong paper will also mention that integrity controls extend beyond the network layer — file hashing, version control, and audit logging are integrity mechanisms at the application and storage layer. Mentioning this shows awareness that defense in depth operates at multiple layers, not just the network.
Availability
Availability means ensuring that authorized users can access systems and data when needed. In your network, availability is relevant to several design decisions: redundant Internet connections (even if not explicitly required, you can propose them), the use of a proxy to cache content and reduce bandwidth consumption on the 3 Mbps remote link, and the firewall rule set which, if misconfigured, can itself become an availability threat (this tension is worth discussing). The IDS also protects availability by detecting denial-of-service attempts early.
Writing Tip: Do not write the CIA triad section as three separate mini-essays with no connection to each other. Tie them together. For example: “The design achieves confidentiality and integrity simultaneously through the VPN, but the encryption overhead on the 3 Mbps remote link creates an availability tradeoff that must be managed.” That kind of integrative analysis is what earns high marks.
Tracing the Data Flow from the Remote Site
The assignment specifies: “Assume data begins at the remote site.” This means your data flow analysis should start at a remote site workstation and trace the path to a resource at the corporate site. Here is how to think through it step by step:
Step-by-Step Data Flow Trace
Remote Workstation Initiates a Request
A remote employee opens a file share hosted on the Chicago file server. The request originates at the workstation’s IP address on the remote site LAN and is directed to the file server’s internal IP address.
Remote Site Firewall / VPN Gateway
The request hits the remote site’s firewall. Because the destination is a corporate resource, the firewall forwards the traffic to the VPN gateway, which encapsulates the packet in an encrypted tunnel. The data is now protected against interception on the Internet segment.
Transit Over the Public Internet
The encrypted VPN packet travels across the public Internet from the remote site’s 3 Mbps link to the Chicago site’s 50 Mbps link. At this stage, the IDS at the Chicago perimeter may log the incoming encrypted session. Because it is encrypted, the IDS monitors metadata (source IP, port, session characteristics) rather than payload content.
Chicago Perimeter Firewall / VPN Termination
The VPN tunnel terminates at the Chicago VPN concentrator. The packet is decrypted, and the perimeter firewall applies its rule set. If the source IP (from the trusted remote site VPN range) and destination port are permitted, the traffic is forwarded to the internal network. The IDS can now inspect the decrypted payload if positioned at this point.
Internal Network and Internal Firewall
The traffic passes the internal firewall. This firewall enforces a stricter rule set between the DMZ and the internal LAN. The file server is on the internal LAN, so the traffic must clear this second control boundary. If the traffic were destined for the web server (in the DMZ), it would have been stopped at this boundary.
File Server Authentication and Access Control
The file server receives the request. The server’s operating system requires authentication (e.g., Active Directory credentials). The IDS may log the access event. The employee’s role-based permissions determine which files or directories can be read or written. This is the application layer of defense.
Response Returns to Remote Site
The file server returns the requested data. The response follows the same path in reverse: internal firewall → VPN encapsulation → Internet → remote site VPN gateway → remote site firewall → workstation. Each boundary applies its controls to the return traffic.
Write this flow in your paper using this logical sequence. For each step, explain which security control is active and why it matters. Then cite a source that supports the relevance of that control. This is what the assignment means by “cite specific, credible sources” for the data flow section.
Finding and Using Four Credible Academic Sources
The assignment requires a minimum of four specific and credible academic sources, each cited at least once in the text. Here is how to find appropriate sources and how to use them effectively rather than just inserting a citation at the end of a paragraph.
Where to Find Sources
- NIST Computer Security Resource Center (csrc.nist.gov): Special Publications (SP 800-series) are authoritative, freely available, and accepted in cybersecurity coursework. SP 800-53 (security controls), SP 800-41 (firewall guidelines), and SP 800-94 (IDS/IPS) are directly relevant to this assignment.
- IEEE Xplore (ieeexplore.ieee.org): Peer-reviewed journal articles and conference papers on network security, defense in depth, and related topics. Many are available through university library access.
- ACM Digital Library (dl.acm.org): Similar to IEEE Xplore for computing and networking research.
- Google Scholar (scholar.google.com): Use this to find peer-reviewed papers. Filter by publication date if you need recent sources. Search terms like “defense in depth network architecture,” “CIA triad information security,” and “network segmentation security” will return relevant results.
- Your University Library Databases: ProQuest, EBSCOhost, and similar databases aggregate academic journals. If your institution provides access, these are your strongest resources for peer-reviewed papers.
How to Synthesize Sources (Not Just Cite Them)
The assignment explicitly asks you to “synthesize” sources “into a coherent analysis of the evidence.” This means you should not just quote a source to prove a point and move on. You should use multiple sources together to build an argument. For example:
Weak citation practice: “Firewalls are important for network security (Smith, 2020).”
Synthesized approach: “Smith (2020) identifies firewalls as the primary perimeter control in enterprise networks, while NIST SP 800-41 provides the specific configuration guidance for stateful inspection rules. When both sources are read together, it is clear that a firewall’s effectiveness depends not on its presence alone but on how its rule set is structured — a principle that directly informs the dual-firewall, DMZ-based architecture in this design.”
For this assignment, our research paper writing service can help you locate, integrate, and properly cite academic sources according to your required citation style (APA, MLA, Chicago, etc.). You can also use our citation and referencing guide to format your reference list correctly.
Common Mistakes in Defense in Depth Assignments
Drawing a Single-Layer Perimeter and Calling It DiD
A single firewall at the edge is perimeter security, not defense in depth. To demonstrate layered security, your diagram must show distinct zones separated by distinct controls — typically a minimum of two firewalls with a DMZ between them, plus internal segmentation via VLANs or subnets, plus endpoint controls. If a grader can identify only one layer of security in your diagram, you have not met the assignment requirements.
Ignoring the Remote Site Security
Students often design the corporate site well and then connect the remote site with a single line labeled “VPN.” The remote site needs its own firewall, its own network structure, and its own security controls. The assignment states that remote employees need access to all corporate resources — that means their traffic must traverse VPN encryption, and the remote site itself must be protected against threats originating locally.
Describing the CIA Triad Without Connecting It to the Design
Defining confidentiality, integrity, and availability from a textbook is not analysis. The assignment asks you to explain “how isolating by network functions helps deliver a layered approach.” Every element of the CIA triad must be connected to a specific design decision in your network. If you cannot point to a device, zone, or policy in your diagram that delivers each property, you have missed the assignment’s analytical requirement.
Data Flow Without Security Checkpoints
Describing data flow as “the packet travels from the remote site to the file server” is a topology description, not an analysis. For each step in the flow, name the security control encountered and explain its function. The IDS mention in the assignment instructions is a hint — they expect you to discuss monitoring as part of the flow.
Insufficient or Poorly Cited Sources
The assignment requires at least four credible academic sources, each cited at least once. Using only web articles, vendor white papers, or Wikipedia will not meet this standard. Peer-reviewed journal articles and NIST publications are the correct standard. Check that every source in your reference list is cited in the body of your paper at least once.
Tools: Microsoft Visio vs. Dia Diagram Editor
The assignment accepts either Microsoft Visio or Dia. Here is what you need to know about each:
Microsoft Visio
The industry-standard tool for network diagrams. Visio has a dedicated “Network” stencil set with standardized icons for routers, firewalls, switches, servers, and more. If your institution provides Microsoft 365 licenses, you likely have access through your student account. The output is a .vsdx file, which can also be exported to PDF or PNG for submission.
Dia Diagram Editor
A free, open-source alternative. Dia includes a Cisco network stencil library that covers most standard network device types. The output is a .dia file, which can be exported to PNG, SVG, or PDF. Quality is lower than Visio in terms of visual polish, but it is fully capable of meeting the assignment requirements.
draw.io / diagrams.net
While not listed in the assignment, draw.io is a free, browser-based diagramming tool that is widely accepted in academic settings. It includes full network shape libraries and can export to PNG, PDF, and Visio formats. If Visio and Dia are both unavailable, confirm with your instructor before using this alternative.
Frequently Asked Questions
How many firewalls should my diagram include?
For a proper defense in depth architecture with a DMZ, you need at minimum two firewalls at the corporate site: one between the Internet and the DMZ, and one between the DMZ and the internal LAN. The remote site should also have its own firewall. That puts the minimum at three firewalls across the full diagram. A two-firewall DMZ setup is the most common architecture referenced in network security textbooks and is likely what your instructor expects to see.
Where exactly should the IDS be placed in the diagram?
The optimal placement depends on what you want the IDS to monitor. Placing it between the external firewall and the DMZ allows it to monitor traffic entering the DMZ. Placing it between the DMZ and the internal LAN allows it to monitor traffic attempting to reach internal resources. Many enterprise designs use multiple IDS sensors. For this assignment, one placement is sufficient, but your paper should explain why you chose that position and what it is designed to detect.
Which servers go in the DMZ and which go on the internal network?
Servers that need to be reachable from the Internet go in the DMZ: the web server, FTP server, and mail server. Servers that should only be accessed by internal or authenticated users belong on the internal network: the file server and print server. This separation is the core purpose of the DMZ — it limits what an attacker can reach even if they compromise a public-facing server.
Does the VPN connection count as one of the security layers in defense in depth?
Yes. The VPN creates an encrypted tunnel that protects data confidentiality and integrity in transit over the public Internet. It is the security control for the “transit” layer of your architecture. In addition to encryption, VPN gateways typically require authentication before establishing a session, which adds an access control layer. You should describe the VPN as both a data-in-transit protection mechanism and an authentication control in your paper.
How long should the data flow section of the paper be?
Roughly 2–3 pages. The data flow section is the most technically detailed part of the paper. You need to trace the packet from the remote workstation through every network boundary to the file server and back, naming each security control and citing sources for its relevance. Rushing this section with a one-page summary will miss the marks allocated to it. Use step-by-step subheadings if your formatting allows it — this makes the flow clear to the reader and easier to grade.
What citation format should I use for NIST publications?
NIST Special Publications are government documents. In APA 7th edition, the citation format is: Author(s), (Year). Title of publication (Publication Number). National Institute of Standards and Technology. https://doi.org/… — Always check your course-required citation style, as the format differs between APA, MLA, and Chicago. Our citation guide covers government documents across the main styles.
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