SAP-C02 Continuous Improvement for Existing Solutions Practice Question

A company is migrating from a monolithic application to microservices on AWS. They need to reduce the blast radius of failures. Which architecture pattern should they implement?

⚠ Common exam trap

The trap is assuming Auto Scaling alone reduces blast radius — scaling improves capacity but does not isolate failure domains if the data store or load balancer is shared.

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

✓

Use a cell-based architecture where each microservice runs in isolated cells with independent data stores.

A cell-based architecture isolates each microservice (or group) into independent cells with their own data stores, so a failure in one cell cannot cascade to others — this directly reduces blast radius. Independent data stores prevent a shared database from becoming a single point of failure and coupling failure domains. This pattern is the AWS-recommended approach for fault isolation in microservices.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Implement Auto Scaling groups for each microservice without separating data stores.
Why it's wrong here
Scaling each microservice independently without separating data stores leaves a shared database as a single point of failure, so one database fault still cascades across services. It is tempting because Auto Scaling groups genuinely improve compute resilience, but that pattern suits stateless tiers, not blast-radius reduction requiring isolated data stores.
✓
Use a cell-based architecture where each microservice runs in isolated cells with independent data stores.
Why this is correct
Cell-based architecture partitions workloads into independent, self-contained cells, each with its own compute and data stores. A failure inside one cell cannot cascade to others, directly shrinking the blast radius, which is the isolation outcome the migration to microservices requires.
✗
Route all traffic through a single Application Load Balancer to simplify management.
Why it's wrong here
A single ALB concentrates all ingress into one component, so its failure takes down every microservice behind it, enlarging rather than reducing blast radius. It is tempting because one load balancer genuinely simplifies certificate and routing management, and would suit a small, low-criticality estate where operational simplicity outweighs fault isolation.
✗
Deploy all microservices in a single Availability Zone with a shared database.
Why it's wrong here
Concentrating every microservice and a shared database in one Availability Zone means a single zone failure takes down the whole application, enlarging rather than reducing blast radius. It is tempting because co-locating services cuts cross-AZ latency and data transfer cost, which suits latency-sensitive single-zone workloads, not resilience goals.

Quick reference

AAA Protocol Comparison

Protocol	Port(s)	Encryption	Transport	Primary Use
RADIUS	1812 / 1813	Password only	UDP	Network access control
TACACS+	49	Full packet	TCP	Device administration
Diameter	3868	Full session	TCP / SCTP	Carrier / mobile networks
802.1X	—	EAP-based	Layer 2	Port-based access control

TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.

Go deeper

SAP-C02 Continuous Improvement for Existing Solutions Practice Question

Why each option matters

Option-by-option breakdown

AAA Protocol Comparison

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