Design and Implement Azure Load Balancer Using the Azure Portal - Training

Summary

The Azure Load Balancer distributes incoming traffic to backend pool instances, which can be Azure Virtual Machines. You can create both public and internal load balancers depending on your needs, and they can be configured for high availability across different zones. To set up a load balancer, you must create it in the Azure portal, add a backend pool, set health probes, and establish load balancing rules.

Highlights

Azure Load Balancer operates at layer 4 of the Open Systems Interconnection (OSI) model. It's the single point of contact for clients. Azure Load Balancer distributes inbound flows that arrive at the load balancer's front end to backend pool instances. These flows are according to configured load-balancing rules and health probes. The backend pool instances can be Azure Virtual Machines or instances in a virtual machine scale set. ([View Highlight] (https://read.readwise.io/read/01j3ps7skya9jwt79g94q2084k))

Azure services that support availability zones fall into three categories:
• Zonal services: Resources can be pinned to a specific zone. For example, virtual machines, managed disks, or standard IP addresses can be pinned to a specific zone, which allows for increased resilience by having one or more instances of resources spread across zones.
• Zone-redundant services: Resources are replicated or distributed across zones automatically. Azure replicates the data across three zones so that a zone failure doesn't impact its availability.
• Non-regional services: Services are always available from Azure geographies and are resilient to zone-wide outages and region-wide outages. ([View Highlight] (https://read.readwise.io/read/01j3y3mqwap5sc3ftkt0j2besa))

Features
Standard Load Balancer
Basic Load Balancer
Backend pool size
Supports up to 1000 instances.
Supports up to 300 instances.
Backend pool endpoints
Any virtual machines or virtual machine scale sets in a single virtual network.
Virtual machines in a single availability set or virtual machine scale set.
Health probes
TCP, HTTP, HTTPS
TCP, HTTP
Health probe down behavior
TCP connections stay alive on an instance probe down and on all probes down.
TCP connections stay alive on an instance probe down. All TCP connections end when all probes are down.
Availability Zones
Zone-redundant and zonal frontends for inbound and outbound traffic.
Not available
Diagnostics
Azure Monitor multi-dimensional metrics
Azure Monitor logs
HA Ports
Available for Internal Load Balancer
Not available
Secure by default
Closed to inbound flows unless allowed by a network security group. Internal traffic from the virtual network to the internal load balancer is allowed.
Open by default. Network security group optional.
Outbound Rules
Declarative outbound NAT configuration
Not available
TCP Reset on Idle
Available on any rule
Not available
Multiple front ends
Inbound and outbound
Inbound only
Management Operations
Most operations < 30 seconds
60-90+ seconds typical
SLA
99.99%
Not available
Microsoft recommends Standard load balancer. Standalone VMs, availability sets, and virtual machine scale sets can be connected to only one SKU, never both. Load balancer and the public IP address SKU must match when you use them with public IP addresses.
SKUs aren't mutable; therefore, you cannot change the SKU of an existing resource. ([View Highlight] (https://read.readwise.io/read/01j3y4cfg59cb9fwp82pk9zder))