AZ-305 Design business continuity solutions Practice Question
A company runs a stateless web application on multiple Azure VMs behind a load balancer. They want to ensure that if a VM fails, traffic is automatically redirected to healthy VMs. Which Azure service provides this functionality with health probes?
⚠ Common exam trap
A common mix-up: candidates confuse Azure Load Balancer with Azure Traffic Manager or Azure Front Door, thinking that any 'load balancing' service can handle VM-level health probes, but only Azure Load Balancer is designed for regional, layer-4 traffic distribution with health probe-based failover for VMs behind a load balancer.
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
✓
Azure Load Balancer
Azure Load Balancer (Option D) is the correct choice because it is designed to distribute traffic across multiple VMs in the same region and uses health probes (TCP or HTTP) to monitor the health of each backend VM. If a probe fails, the load balancer automatically stops sending new traffic to that VM and redirects it to the remaining healthy instances, ensuring high availability for the stateless web application.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Azure Traffic Manager
Why it's wrong here
Azure Traffic Manager operates at the DNS level, resolving client queries to regional endpoints rather than directly routing packets to VM instances. Its health checks verify availability of the monitored endpoint as a whole, not the individual virtual machines behind a load balancer, so it cannot reroute traffic away from a failed VM within a single region. For this scenario, you need a regional Layer 4 load balancer with per-VM health probes.
- ✗
Azure Front Door
Why it's wrong here
Azure Front Door operates at the application layer (HTTP/HTTPS) and is designed for global load balancing and web application acceleration across regions, not for rerouting traffic among VMs within a single Azure region behind a load balancer. The scenario requires a regional load balancer that uses health probes to detect VM failure and redirect traffic at Layer 4 (TCP/UDP) or Layer 7 within the same region. Front Door would be correct if the need were to distribute traffic across multiple regional endpoints or to provide global failover with path-based routing.
- ✗
Azure Application Gateway
Why it's wrong here
Application Gateway uses Layer 7 routing and HTTP/HTTPS health probes, but the scenario requires only basic VM health monitoring behind a load balancer, which is a Layer 4 function. It is tempting because its health probes can redirect traffic away from failed VMs, yet it introduces unnecessary protocol-level inspection and SSL termination. It would be correct if the application needed URL-based routing or web application firewall capabilities.
- ✓
Azure Load Balancer
Why this is correct
Azure Load Balancer provides Layer 4 (TCP/UDP) load balancing for inbound traffic to a backend pool of VMs in the same region, distributing flows according to the configured rule. It continuously runs health probes against each VM and automatically removes any VM that fails its probe, sending subsequent traffic only to healthy instances. This satisfies the requirement for basic VM health monitoring and automatic rerouting without adding Layer 7 features like URL inspection or SSL termination.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-305 practice question is part of Courseiva's free Microsoft 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 AZ-305 exam.