Azure Load Balancer
The deployment of Azure Load Balancer involves the coordinated configuration of several groups of settings. These settings work together to define the overall Load Balancer behavior.
BASIC AND STANDARD LOAD BALANCER TIERS
Azure Load Balancer is available in two pricing tiers (SKUs): Basic and Standard. These tiers offer different levels of scale, features, and pricing. Table 4-8 provides a comparison of the main feature differences between the Basic and Standard tiers.
TABLE 4-8 Standard and Basic Load Balancer tiers
| Feature | Standard | Basic |
| Availability Zones | Supports zone-specific or zone- redundant deployments, including cross-zone load balancing | Not supported |
| Backend Pools | Up to 5,000 servers, any mix of VMs, availability sets, and VM Scale Sets— in the same VNet | Up to 300 IP configurations Must be VMs in the same availabil- ity set or a single VM Scale Set |
| Health Probes | TCP, HTTP, HTTPS | TCP, HTTP |
| Diagnostics | Rich metrics via Azure Monitor, including byte and packet counters, health probe status, connection attempts, outbound connection health, and more | Not supported |
| Security | Inbound flows closed by default Whitelist-permitted inbound flows using Network Security Groups | Open by default Can optionally restrict flows using Network Security Groups |
| Outbound Connectivity | Supports multiple outbound IP addresses that are configurable via outbound rules | Single outbound IP Not configurable |
| Other Features | Supports HA Ports, TCP Reset on idle timeout, and faster management operations | N/A |
| Pricing | Based on the number of rules and data processed | Free |
| SLA | 99.99 percent availability for a data path with two healthy VMs | None |
FRONTEND IP CONFIGURATION
Azure Load Balancer supports two modes: Internal Load Balancer and Public Load Balancer. In each case, the frontend IP configuration defines the endpoint upon which the load balancer receives incoming traffic:
- Internal Load Balancer Used to load-balance traffic for intranet-facing applications, or between application tiers. The frontend IP configuration references a subnet, and an IP address from that subnet is allocated using either dynamic or static assignment to the load balancer.
- Public Load Balancer Used to load-balance traffic for internet-facing applications. The frontend IP configuration references a separate public IP address resource, which is used to receive inbound traffic.
When used with IaaS VMs, each load balancer can support multiple frontend IP configu- rations. Therefore, it can receive traffic on multiple IP addresses to load-balance traffic for multiple applications. All frontend configurations, however, must be of the same type: internal or public.
A public load balancer must be associated with a public IP address resource. If the load balancer uses the Standard pricing tier, then the public IP address must also use the Standard pricing tier. Standard-tier load balancers support both zone-specific and zone-redundant deployment options. The choice of deployment option is taken from the associated public IP address, rather than being explicitly in the load balancer properties.