Explore Azure load balancer
You can use the platform-provided Azure load balancer to enhance availability and scalability of virtual machines by configuring them as a load-balanced set. Azure load balancer provides functionality similar to hardware load balancers by eliminating single points of failure (application or hardware), increasing uptime during planned maintenance or upgrades, and distributing workloads across multiple, identically configured compute nodes.
Azure load balancer can handle traffic originating from within the same Azure virtual network, from any directly connected network, or from the internet. In addition, you can configure it to implement the network address translation (NAT) capability, providing connections to individual virtual machines in the load-balanced set.
Azure load balancer is available in two SKUs: Basic and Standard.
Standard load balancer
Basic load balancer
Scenario
Equipped for load-balancing network layer traffic when high performance and ultra-low latency is needed. Routes traffic within and across regions, and to availability zones for high resiliency.
Equipped for small-scale applications that don't need high availability or redundancy. Not compatible with availability zones.
Backend type
IP based, NIC based
NIC based
Protocol
TCP, UDP
TCP, UDP
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.
TCP, HTTP, HTTPS
TCP, HTTP
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
Not supported
HA ports
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
Not available
TCP reset on idle
Not available
Inbound and outbound
Inbound only
Management operations
Most operations < 30 seconds
60-90+ seconds typical
SLA
Not available
Global VNet Peering Support
Standard ILB is supported via Global VNet Peering
Not supported
Both Standard ILB and Standard Public LB are supported via Nat Gateway
Not supported
Standard ILB is supported via Private Link
Not supported
Standard LB supports the Global tier for Public LBs enabling cross-region load balancing
Not supported
Limitations
- SKUs aren't mutable. You can't change the SKU of an existing resource.
- A standalone virtual machine resource, availability set resource, or virtual machine scale set resource can reference one SKU, never both.