hardMultiple ChoiceObjective-mapped
CISSP Practice Question: A development team is implementing a…
A development team is implementing a microservices architecture. Which of the following is the BEST approach to secure inter-service communication?
⚠ Common exam trap
ISC2 often tests the misconception that an API gateway secures all inter-service communication, but candidates forget that east-west traffic between microservices bypasses the gateway and requires its own security mechanism like mTLS.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement mutual TLS (mTLS) between services
Mutual TLS (mTLS) is the best approach because it provides both encryption and bidirectional authentication between services, ensuring that only authorized services can communicate. Unlike token-based methods, mTLS verifies the identity of both the client and server using X.509 certificates, which is critical in a zero-trust microservices environment where network boundaries are porous.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use JSON Web Tokens (JWT) for each request
Why it's wrong here
JSON Web Tokens (JWTs) primarily serve as a mechanism for authenticating and authorizing requests by securely transmitting claims about a user or service. While they ensure the integrity and authenticity of the token's payload through cryptographic signatures, JWTs themselves do not encrypt the communication channel. Therefore, without an underlying secure transport layer like TLS, the token and the entire request payload remain vulnerable to interception and exposure during transit between microservices.
- ✗
Use API keys transmitted in HTTP headers
Why it's wrong here
API keys offer a simple method for client authentication, typically identifying the calling application or service. However, they are essentially static credentials and provide no inherent encryption for the data exchanged over the network. Furthermore, API keys only authenticate the client to the server, lacking mutual authentication where both parties verify each other's identity, which leaves the communication susceptible to impersonation and eavesdropping if the key is compromised or intercepted.
- ✗
Place all services behind a single API gateway
Why it's wrong here
An API gateway acts as an essential entry point for external traffic into a microservices architecture, handling concerns like routing, authentication, and rate limiting for requests originating outside the system. While it secures the perimeter and protects individual services from direct exposure, it does not inherently secure the internal, service-to-service communication paths once a request has passed through. This leaves internal network traffic between microservices vulnerable to attacks like eavesdropping or tampering within the trusted network boundary.
- ✓
Implement mutual TLS (mTLS) between services
Why this is correct
Mutual TLS (mTLS) is a robust security protocol that establishes strong, bidirectional authentication and encryption for network communication. It mandates that both the client and the server present and validate cryptographic certificates before any data exchange occurs, ensuring that each microservice verifies the identity of the other. This process guarantees confidentiality, integrity, and authenticity for all inter-service communication, effectively preventing unauthorized access, data tampering, and eavesdropping within the microservices environment.
Go deeper
Related to this question
Learn chapter
Security Architecture and Models
Key term
Encryption
Encryption is the process of converting readable data into a secret code to prevent unauthorized access.
Key term
Authentication
Authentication is the process of verifying that someone or something is who or what it claims to be before granting access to a system or resource.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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