easyMultiple SelectObjective-mapped
High Availability Across Availability Zones
A cloud architect is designing a multi-tier application that must remain available during a single Availability Zone failure. Which TWO design principles should the architect apply?
Quick Answer
The correct answer is to use an auto-scaling group with a minimum of two instances spread across zones. This design ensures high availability across availability zones by distributing workload across physically separate, isolated data centers within a region, so if one zone fails, the other instance continues serving traffic without interruption. On the CompTIA Cloud+ CV0-004 exam, this principle tests your understanding of fault tolerance and redundancy at the infrastructure layer, often appearing in scenario-based questions where a single zone failure must not cause total application downtime. A common trap is choosing a single large instance in one zone or relying solely on load balancing without multi-zone distribution, which still creates a single point of failure. Remember the memory tip: “Two zones, two instances—never put all eggs in one data center basket.”
⚠ Common exam trap
CompTIA often tests the distinction between high availability (within a region across AZs) and disaster recovery (across regions), leading candidates to mistakenly choose synchronous replication (Option A) for AZ failure scenarios when it is actually designed for regional outages.
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
✓
Deploy resources across multiple Availability Zones.
Deploying resources across multiple Availability Zones (AZs) ensures that if one AZ fails, the application continues to run using resources in the other AZ(s). This is a fundamental principle of high availability in cloud architecture, as AZs are isolated from each other's failures. Option E complements this by using an auto-scaling group with a minimum of two instances spread across zones, which maintains capacity even if one instance or AZ fails.
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 synchronous replication between the primary site and a DR site.
Why it's wrong here
This does not protect against an Availability Zone failure within the primary region.
- ✓
Deploy resources across multiple Availability Zones.
Why this is correct
This provides redundancy if one zone fails.
- ✗
Use a single load balancer to distribute traffic across instances.
Why it's wrong here
A single load balancer creates a single point of failure; if the Availability Zone hosting it fails, all traffic distribution ceases, violating the requirement for continued availability during a single zone failure. It is tempting because a load balancer normally ensures high availability by distributing traffic across healthy instances within a single region, which would be correct if the requirement were only to handle instance-level failures, not an entire zone outage.
- ✗
Place all application servers in the same subnet for low latency.
Why it's wrong here
Placing all servers in one subnet creates a single point of failure.
- ✓
Use an auto-scaling group with a minimum of two instances spread across zones.
Why this is correct
This ensures capacity is maintained even if one zone fails.
Go deeper
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About these practice questions
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Same concept, more angles
1 more way this is tested on CV0-004
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is migrating its on-premises application to the cloud and needs to ensure high availability. The application requires a stateless web tier and a stateful database tier. Which design approach BEST meets these requirements?
easy- A.Deploy one large web server and one large database server.
- ✓ B.Deploy web servers behind a load balancer and use a managed database with multi-AZ replication.
- C.Use round-robin DNS for web servers and a read replica for the database.
- D.Use auto-scaling for web servers and a single database instance.
Why B: Deploying web servers behind a load balancer provides horizontal scaling and fault tolerance for the stateless web tier, while using a managed database with multi-AZ replication ensures automatic failover and data durability for the stateful database tier. This combination meets high availability requirements by eliminating single points of failure and providing redundancy across Availability Zones.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CV0-004 exam.