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1 | 1 | --- |
2 | 2 | title: What is Azure Load Balancer? |
3 | 3 | titleSuffix: Azure Load Balancer |
4 | | -description: Get an overview of Azure Load Balancer features, architecture, and implementation. Learn how the service works and how to use it in the cloud. |
| 4 | +description: Learn what Azure Load Balancer is, its key features, and how it supports scalable, highly available cloud workloads. Discover scenarios and benefits for your organization. |
5 | 5 | services: load-balancer |
6 | 6 | author: mbender-ms |
7 | 7 | ms.service: azure-load-balancer |
8 | 8 | ms.topic: overview |
9 | | -ms.date: 02/19/2024 |
| 9 | +ms.date: 05/14/2025 |
10 | 10 | ms.author: mbender |
11 | | -ms.custom: template-overview, engagement-fy23 |
12 | | -# Customer intent: As an IT administrator, I want to learn more about the Azure Load Balancer service and what I can use it for. |
| 11 | +ms.custom: portfolio-consolidation-2025 |
| 12 | +#customer intent: As an IT administrator, I want to understand what Azure Load Balancer is so that I can decide if it fits my organization's needs. |
13 | 13 | --- |
14 | 14 |
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15 | 15 | # What is Azure Load Balancer? |
16 | 16 |
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17 | | ->[!Important] |
| 17 | +> [!Important] |
18 | 18 | >On September 30, 2025, Basic Load Balancer will be retired. For more information, see the [official announcement](https://azure.microsoft.com/updates/azure-basic-load-balancer-will-be-retired-on-30-september-2025-upgrade-to-standard-load-balancer/). If you are currently using Basic Load Balancer, make sure to upgrade to Standard Load Balancer prior to the retirement date. For guidance on upgrading, visit [Upgrading from Basic Load Balancer - Guidance](load-balancer-basic-upgrade-guidance.md). |
19 | 19 |
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| 20 | +Azure Load Balancer is a cloud service that distributes incoming network traffic across backend virtual machines (VMs) or virtual machine scale sets (VMSS). This article explains Azure Load Balancer's key features, architecture, and scenarios, helping you decide if it fits your organization's load balancing needs for scalable, highly available workloads. |
| 21 | + |
20 | 22 | *Load balancing* refers to efficiently distributing incoming network traffic across a group of backend virtual machines (VMs) or virtual machine scale sets (VMSS). |
21 | 23 |
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| 24 | +> [!NOTE] |
| 25 | +> Azure Load Balancer is one of the services that make up the Load Balancing and Content Delivery category in Azure. Other services in this category include [Azure Front Door](../frontdoor/front-door-overview.md) and [Azure Application Gateway](../application-gateway/overview.md). Each service has its own unique features and use cases. For more information on this service category, see [Load Balancing and Content Delivery](../networking/load-balancer-content-delivery/load-balancing-content-delivery-overview.md). |
| 26 | +
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| 27 | +## Load balancer overview |
| 28 | + |
22 | 29 | Azure Load Balancer operates at layer 4 of the Open Systems Interconnection (OSI) model. It's the single point of contact for clients. The service distributes inbound flows that arrive at the load balancer's frontend to backend pool instances. These flows are distributed according to configured load-balancing rules and health probes. The backend pool instances can be Azure virtual machines (VMs) or virtual machine scale sets. |
23 | 30 |
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24 | 31 | A [public load balancer](./components.md#frontend-ip-configurations) can provide both inbound and outbound connectivity for the VMs inside your virtual network. For inbound traffic scenarios, Azure Load Balancer can load balance internet traffic to your VMs. For outbound traffic scenarios, the service can translate the VMs' private IP addresses to public IP addresses for any outbound connections that originate from your VMs. |
25 | 32 |
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26 | | -Alternatively, an [internal (or private) load balancer](./components.md#frontend-ip-configurations) can provide inbound connectivity to your VMs in private network connectivity scenarios, such as accessing a load balancer frontend from an on-premises network in a hybrid scenario. Internal load balancers are used to load balance traffic inside a virtual network. |
| 33 | +Alternatively, an [internal (or private) load balancer](./components.md#frontend-ip-configurations) are used to load balance traffic inside a virtual network. With internal load balancer, you can provide inbound connectivity to your VMs in private network connectivity scenarios, such as accessing a load balancer frontend from an on-premises network in a hybrid scenario. |
27 | 34 |
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28 | | -:::image type="content" source="media/load-balancer-overview/load-balancer.png" alt-text="Diagram that depicts a load balancer directing traffic."::: |
| 35 | +:::image type="content" source="media/load-balancer-overview/load-balancer.png" alt-text="Screenshot of a diagram showing Azure Load Balancer directing network traffic to backend virtual machines."::: |
29 | 36 |
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30 | 37 | For more information on the service's individual components, see [Azure Load Balancer components](./components.md). |
31 | 38 |
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32 | 39 | Azure Load Balancer has three stock-keeping units (SKUs) - Basic, Standard, and Gateway. Each SKU is catered towards a specific scenario and has differences in scale, features, and pricing. For more information, see [Azure Load Balancer SKUs](skus.md). |
33 | 40 |
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34 | | -## Why use Azure Load Balancer? |
| 41 | +## Why use Azure Load Balancer |
35 | 42 |
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36 | 43 | With Azure Load Balancer, you can scale your applications and create highly available services. |
37 | 44 |
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@@ -71,7 +78,7 @@ Key scenarios that you can accomplish by using Azure Standard Load Balancer incl |
71 | 78 |
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72 | 79 | - [Standard Load Balancer](https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/load-balancer/skus.md) is part of your virtual network, which is private and isolated for security. |
73 | 80 |
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74 | | -- Standard load balancers and standard public IP addresses are closed to inbound connections, unless network security groups (NSGs) open them. You use NSGs to explicitly permit allowed traffic. If you don't have an NSG on a subnet or network interface card (NIC) of your virtual machine resource, traffic is not allowed to reach the resource. To learn about NSGs and how to apply them to your scenario, see [Network security groups](../virtual-network/network-security-groups-overview.md). |
| 81 | +- Standard load balancers and standard public IP addresses are closed to inbound connections, unless network security groups (NSGs) open them. You use NSGs to explicitly permit allowed traffic. If you don't have an NSG on a subnet or network interface card (NIC) of your virtual machine resource, traffic isn't allowed to reach the resource. To learn about NSGs and how to apply them to your scenario, see [Network security groups](../virtual-network/network-security-groups-overview.md). |
75 | 82 |
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76 | 83 | - [Basic Load Balancer](https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/load-balancer/skus.md) is open to the internet by default. |
77 | 84 |
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