The answer is to distribute incoming network traffic across multiple backend resources for high availability. Azure Load Balancer operates at Layer 4 of the OSI model, using a 5-tuple hash (source IP, source port, destination IP, destination port, and protocol) to evenly spread TCP or UDP traffic across healthy virtual machines in a backend pool. This ensures no single resource is overwhelmed, while health probes automatically route traffic away from failed instances, providing fault tolerance and scalability. On the AZ-900 exam, this concept tests your understanding of how Azure achieves high availability through traffic distribution, often appearing in scenario-based questions about load balancing versus application gateways. A common trap is confusing Layer 4 (Load Balancer) with Layer 7 (Application Gateway); remember that Load Balancer only sees IPs and ports, not HTTP headers. Memory tip: think "Layer 4 Load Balancer = 4-tuple plus protocol equals 5-tuple hash."
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
To distribute incoming network traffic across multiple backend resources
Azure Load Balancer operates at Layer 4 (TCP/UDP) of the OSI model to distribute incoming traffic across healthy backend resources, such as virtual machines or instances in a backend pool. It uses a hash-based distribution algorithm (5-tuple hash for inbound traffic) to ensure high availability and scalability by spreading requests evenly. This directly supports fault tolerance by automatically routing traffic away from unhealthy instances based on health probes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
To cache web content at edge locations globally
Why it's wrong here
Content caching at edge locations is provided by Azure CDN, not Load Balancer.
✓
To distribute incoming network traffic across multiple backend resources
Why this is correct
Load Balancer distributes TCP/UDP traffic across healthy backend VMs for high availability.
Related concept
Read the scenario before looking for a memorised answer.
DNS management is done by Azure DNS and Traffic Manager, not Load Balancer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure Load Balancer with Azure Traffic Manager or Azure Application Gateway, but Load Balancer operates at Layer 4 (TCP/UDP) for regional traffic distribution, not at Layer 7 (HTTP/HTTPS) or for global DNS-based routing.
Detailed technical explanation
How to think about this question
Azure Load Balancer supports both public and internal load balancing, using a 5-tuple hash (source IP, source port, destination IP, destination port, protocol) to map traffic to backend servers, ensuring session persistence when combined with source IP affinity. Health probes (HTTP, TCP, or HTTPS) are sent at configurable intervals (default 5 seconds) to detect backend pool member status; if a probe fails consecutively (default 2 failures), the instance is removed from rotation. In a real-world scenario, a multi-tier application might use an internal load balancer to distribute database traffic across SQL replicas while a public load balancer handles web tier requests.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: To distribute incoming network traffic across multiple backend resources — Azure Load Balancer operates at Layer 4 (TCP/UDP) of the OSI model to distribute incoming traffic across healthy backend resources, such as virtual machines or instances in a backend pool. It uses a hash-based distribution algorithm (5-tuple hash for inbound traffic) to ensure high availability and scalability by spreading requests evenly. This directly supports fault tolerance by automatically routing traffic away from unhealthy instances based on health probes.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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