AZ-104 Microsoft Azure Administrator Exam

Understand Load Balancer Types and Use Cases

Azure Load Balancer is a critical service that helps manage incoming network traffic efficiently by distributing it across different backend resources, such as virtual machines (VMs) or virtual machine scale sets (VMSS). Operating at layer 4 of the OSI model, it acts as a single point of contact for clients, using load-balancing rules and health probes to ensure smooth operation. By directing inbound flows to backend pool instances, it provides reliability and scalability for applications.

Types of Load Balancers

Azure offers two main types of load balancers, each serving distinct purposes. The Public Load Balancer manages inbound and outbound connectivity for VMs within a virtual network. It is mainly used for balancing internet traffic to VMs, offering public IP address translation for outbound connections. Conversely, the Internal (Private) Load Balancer manages traffic within a virtual network, supporting private network scenarios like hybrid setups where on-premises networks access a load balancer frontend.

Load Balancer SKUs

Azure Load Balancer is available in three SKUs: Basic, Standard, and Gateway. These SKUs cater to different needs regarding scale, features, and pricing. Notably, the Basic SKU will be retired on September 30, 2025, urging users to migrate to the more advanced Standard SKU. Each SKU provides specific capabilities that align with diverse use cases and performance requirements.

Key Features and Use Cases

The Azure Load Balancer supports varied scenarios, handling large volumes of TCP and UDP flows with low latency and high throughput. Its main use cases include:

• Load Balancing Traffic: Both internal and external traffic directed to Azure VMs.
• High Availability: Ensuring resource availability through distribution within zones.
• Outbound Connectivity: Managing outbound connections from Azure VMs.
• Health Probes: Verifying the health status of load-balanced resources.
• Port Forwarding: Accessing VMs in a virtual network via public IPs.
• IPv6 Support: Facilitating IPv6 traffic load balancing.
• Metrics and Diagnostics: Providing performance insights through Azure Monitor.

Security and Best Practices

The Standard Load Balancer is designed according to the Zero Trust network security model, operating within your virtual network to ensure privacy and isolation. By default, it is closed to inbound connections unless explicitly configured using Network Security Groups (NSGs). In contrast, the Basic Load Balancer is open to the internet by default, necessitating careful configuration to safeguard against unauthorized access.

Conclusion

The Azure Load Balancer proves to be a versatile tool, enhancing both the reliability and scalability of applications by efficiently managing network traffic. With its ability to handle internal traffic management and public-facing applications alike, it ensures high availability and optimized performance across a range of scenarios. It thus plays an instrumental role in maintaining seamless application delivery within Azure environments.