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WGU D487 OA Test Bank 3 2026/2027 Actual Exam |
420 Questions and Correct Answers with Detailed
Rationales | Secure Software Design Objective
Assessment | Pass Guaranteed - A+ Graded
Section 1: Secure Software Design Fundamentals
Q1: The principle of least privilege means that:
A. Users should have the minimum level of access necessary to perform their functions
[CORRECT]
B. Users should have full access to all systems
C. Users should have no access to any systems
D. Users should share administrative accounts
Correct Answer: A
Rationale: The principle of least privilege grants users the minimum access necessary to perform
their functions. Options B, C, and D violate this principle.
Q2: Which security principle advocates for using multiple layers of security controls to protect
assets?
A. Least Privilege
B. Defense in Depth [CORRECT]
C. Security through Obscurity
D. Single Point of Failure
Correct Answer: B
Rationale: Defense in Depth involves layering security controls so that if one fails, others are in
place to stop an attack. Security through Obscurity (C) is a flawed approach relying on secrecy.
,2
Q3: A system is designed to default to a secure state if an error or exception occurs. This is an
example of:
A. Fail-safe [CORRECT]
B. Fail-open
C. Fail-secure
D. Failsafe defaults
Correct Answer: A
Rationale: Fail-safe (or fail-secure) design ensures that if a system fails, it defaults to a secure
state (e.g., a firewall blocking all traffic if it crashes). Fail-open would allow traffic through upon
failure, which is insecure.
Q4: The "Economy of Mechanism" principle in secure design states that:
A. Security mechanisms should be as complex as possible
B. Security mechanisms should be simple and small [CORRECT]
C. Security mechanisms should be expensive
D. Security mechanisms should be transparent
Correct Answer: B
Rationale: Economy of Mechanism implies that simple designs are easier to inspect, test, and
verify. Complexity increases the attack surface.
Q5: Separation of duties is primarily implemented to prevent:
A. External hackers
B. Fraud and error [CORRECT]
C. System crashes
D. Network latency
,3
Correct Answer: B
Rationale: Separation of duties ensures that a single individual cannot control all aspects of a
critical process, thereby reducing the risk of fraud or error going undetected.
Q6: What is the primary goal of "Complete Mediation"?
A. Checking permissions only at login
B. Verifying permissions for every access to every object [CORRECT]
C. Mediating network traffic only
D. Arbitrating user disputes
Correct Answer: B
Rationale: Complete Mediation ensures that access rights are checked for every access,
preventing attackers from bypassing the check once authenticated.
Q7: "Open Design" refers to the principle that:
A. The security of a system should not depend on the secrecy of its design [CORRECT]
B. The design should be open to the public for editing
C. Open-source software is always insecure
D. Closed-source software is always secure
Correct Answer: A
Rationale: Open Design suggests that security should rely on the secrecy of specific
keys/passwords, not the secrecy of the design itself (Kerckhoffs's principle).
Q8: Which design principle suggests keeping users from knowing the internal workings of a
system?
A. Least Common Mechanism
B. Psychological Acceptability
, 4
C. Work Factor
D. Least Knowledge (Need to Know) [CORRECT]
Correct Answer: D
Rationale: Also known as Information Hiding or Encapsulation, this limits the knowledge a user
or component has about the system, reducing the chance of exploiting that knowledge.
Q9: The "Weakest Link" principle in security architecture suggests:
A. Strengthening the strongest component
B. The security of the system is equal to its weakest component [CORRECT]
C. Security is irrelevant
D. All components are equally strong
Correct Answer: B
Rationale: Attackers will target the easiest point of entry. Security is only as strong as the
weakest link.
Q10: A trusted computing base (TCB) consists of:
A. All hardware, firmware, and software critical to security [CORRECT]
B. Only the hardware
C. Only the application software
D. Network switches
Correct Answer: A
Rationale: The TCB is the set of all hardware, firmware, and/or software components critical to
its security. Failures in the TCB compromise the entire system.
Q11: "Least Common Mechanism" means:
WGU D487 OA Test Bank 3 2026/2027 Actual Exam |
420 Questions and Correct Answers with Detailed
Rationales | Secure Software Design Objective
Assessment | Pass Guaranteed - A+ Graded
Section 1: Secure Software Design Fundamentals
Q1: The principle of least privilege means that:
A. Users should have the minimum level of access necessary to perform their functions
[CORRECT]
B. Users should have full access to all systems
C. Users should have no access to any systems
D. Users should share administrative accounts
Correct Answer: A
Rationale: The principle of least privilege grants users the minimum access necessary to perform
their functions. Options B, C, and D violate this principle.
Q2: Which security principle advocates for using multiple layers of security controls to protect
assets?
A. Least Privilege
B. Defense in Depth [CORRECT]
C. Security through Obscurity
D. Single Point of Failure
Correct Answer: B
Rationale: Defense in Depth involves layering security controls so that if one fails, others are in
place to stop an attack. Security through Obscurity (C) is a flawed approach relying on secrecy.
,2
Q3: A system is designed to default to a secure state if an error or exception occurs. This is an
example of:
A. Fail-safe [CORRECT]
B. Fail-open
C. Fail-secure
D. Failsafe defaults
Correct Answer: A
Rationale: Fail-safe (or fail-secure) design ensures that if a system fails, it defaults to a secure
state (e.g., a firewall blocking all traffic if it crashes). Fail-open would allow traffic through upon
failure, which is insecure.
Q4: The "Economy of Mechanism" principle in secure design states that:
A. Security mechanisms should be as complex as possible
B. Security mechanisms should be simple and small [CORRECT]
C. Security mechanisms should be expensive
D. Security mechanisms should be transparent
Correct Answer: B
Rationale: Economy of Mechanism implies that simple designs are easier to inspect, test, and
verify. Complexity increases the attack surface.
Q5: Separation of duties is primarily implemented to prevent:
A. External hackers
B. Fraud and error [CORRECT]
C. System crashes
D. Network latency
,3
Correct Answer: B
Rationale: Separation of duties ensures that a single individual cannot control all aspects of a
critical process, thereby reducing the risk of fraud or error going undetected.
Q6: What is the primary goal of "Complete Mediation"?
A. Checking permissions only at login
B. Verifying permissions for every access to every object [CORRECT]
C. Mediating network traffic only
D. Arbitrating user disputes
Correct Answer: B
Rationale: Complete Mediation ensures that access rights are checked for every access,
preventing attackers from bypassing the check once authenticated.
Q7: "Open Design" refers to the principle that:
A. The security of a system should not depend on the secrecy of its design [CORRECT]
B. The design should be open to the public for editing
C. Open-source software is always insecure
D. Closed-source software is always secure
Correct Answer: A
Rationale: Open Design suggests that security should rely on the secrecy of specific
keys/passwords, not the secrecy of the design itself (Kerckhoffs's principle).
Q8: Which design principle suggests keeping users from knowing the internal workings of a
system?
A. Least Common Mechanism
B. Psychological Acceptability
, 4
C. Work Factor
D. Least Knowledge (Need to Know) [CORRECT]
Correct Answer: D
Rationale: Also known as Information Hiding or Encapsulation, this limits the knowledge a user
or component has about the system, reducing the chance of exploiting that knowledge.
Q9: The "Weakest Link" principle in security architecture suggests:
A. Strengthening the strongest component
B. The security of the system is equal to its weakest component [CORRECT]
C. Security is irrelevant
D. All components are equally strong
Correct Answer: B
Rationale: Attackers will target the easiest point of entry. Security is only as strong as the
weakest link.
Q10: A trusted computing base (TCB) consists of:
A. All hardware, firmware, and software critical to security [CORRECT]
B. Only the hardware
C. Only the application software
D. Network switches
Correct Answer: A
Rationale: The TCB is the set of all hardware, firmware, and/or software components critical to
its security. Failures in the TCB compromise the entire system.
Q11: "Least Common Mechanism" means:
