The correct answer is OAuth 2.0 with scopes and rate limiting. This combination works because OAuth 2.0 provides delegated, token-based authorization with scopes that enforce fine-grained access control for each microservice, while rate limiting protects the gateway from abuse by throttling excessive requests. On the CISSP exam, this question tests your understanding of the defense-in-depth principle applied to API gateways in microservices architectures—a common scenario in the Communication and Network Security domain. A frequent trap is choosing HTTPS alone, which only encrypts data in transit but does not authorize users, or basic auth, which exposes credentials. Remember the mnemonic “OAuth for who, rate for how many” to recall that OAuth controls identity and permissions, while rate limiting controls traffic volume.
CISSP Software Development Security Practice Question
This CISSP practice question tests your understanding of software development security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An API gateway is being designed for a set of microservices. Which combination of security controls should be implemented?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OAuth 2.0 with scopes and rate limiting
Option D is correct because OAuth 2.0 with scopes provides fine-grained authorization, and rate limiting prevents abuse. Option A is wrong because basic auth sends credentials in plaintext. Option B is wrong because HTTPS alone does not authorize. Option C is wrong because no authentication leaves the API open.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
HTTP Basic Authentication over HTTPS
Why it's wrong here
Basic auth is not suitable for API gateways due to credential exposure.
✗
TLS encryption with anonymous access
Why it's wrong here
Encryption without authentication is insufficient.
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CISSP questions on access control and AAA configuration.
Software Development Security — This question tests Software Development Security — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: OAuth 2.0 with scopes and rate limiting — Option D is correct because OAuth 2.0 with scopes provides fine-grained authorization, and rate limiting prevents abuse. Option A is wrong because basic auth sends credentials in plaintext. Option B is wrong because HTTPS alone does not authorize. Option C is wrong because no authentication leaves the API open.
What should I do if I get this CISSP question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related CISSP questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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Question Discussion
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