📖 What is Azure Load Balancer?
Azure Load Balancer distributes incoming network traffic across multiple virtual machine instances, enhancing application availability and scalability. Operating at Layer 4, it supports TCP, UDP, and HTTP/HTTPS protocols. It provides health probes to ensure traffic is directed only to healthy instances.
"Distinguish between Azure Load Balancer and Application Gateway. Load Balancer operates at Layer 4, while Application Gateway operates at Layer 7 (HTTP/HTTPS) and provides features like web application firewall (WAF). Understand the difference between internal and public load balancing scenarios."
📚 Certification: Microsoft Azure Fundamentals (AZ-900)
🔑 What are the Key Concepts of Azure Load Balancer?
- ▸ Azure Load Balancer distributes traffic based on source IP hash, ensuring session affinity within a single subnet.
- ▸ It operates at the Transport layer (Layer 4) and doesn't inspect application-level data like HTTP headers.
- ▸ Health probes are crucial; they monitor backend instance health and remove unhealthy instances from the rotation.
- ▸ Load Balancers can be internal (private IP addresses) or public (public IP addresses) depending on access requirements.
- ▸ Standard Load Balancers offer features like outbound rules and zone redundancy for higher availability and scalability.
🎯 How does Azure Load Balancer appear on the AZ-900 Exam?
You may be asked to identify the Azure service best suited for distributing traffic to multiple VMs hosting a web application, ensuring high availability and responsiveness.
A scenario might describe a need to distribute UDP traffic for a gaming application – determine which Azure service fulfills this requirement.
Expect questions about configuring health probes to ensure only healthy VMs receive traffic, and how to troubleshoot failed probes.
❓ Frequently Asked Questions
When would I choose an Azure Load Balancer over an Application Gateway?
Use Load Balancer for non-HTTP/HTTPS traffic (TCP, UDP) or when you need Layer 4 load balancing. Application Gateway is better for web traffic needing features like WAF and URL-based routing.
What is the difference between a public and internal Load Balancer?
A public Load Balancer has a public IP address and is accessible from the internet. An internal Load Balancer uses private IPs and distributes traffic within a virtual network.
How do outbound rules work with Azure Load Balancers?
Outbound rules allow you to specify how VMs send traffic to the internet, using a specific public IP address or NAT gateway, enhancing security and control over egress traffic.