Load Balancer Options

All load balancers are software appliances (software defined networking: SDN)
💡 Only Standard (not Basic) SKU allows availability zones in Load balancer

Public Load Balancer

OSI Layer 4 TCP and UDP
Internet-facing, has public IP address
Offers two distribution modes
Set-up public load balancer
1. Settings -> Back-end-pools-> Add VMs
2. Settings -> Health-probe -> Add health probe
  - E.g. tcp-80-probe (HTTP) probe
  - Set interval -> time between prop events
  - Set unhealth threshold (e.g. 2) before VM is dropped out from the pool
  - Add load balancing port
  - Incoming request from port 80 (port) will be passed to TCP passed 80 (back-end port)
  - Select backend pool & health-probe
  - Set session persistance
  - Floating IP (direct server return)
    - Use with internal load balancers
    - Use with SQL server always on cluster
    - Used when same back-end port needs to be used across multiple rules in a single Load Balancer.
3. Add inbound NAT rule
  - Map TCP 5000 to a VMs RDP port (3389)
  - Map TCP 5000 to a VMs RDP port (3389)

Internal load balancer

OSI Layer 4 TCP and UDP
Applies to traffic only within a virtual network
- No public IP address
Good for applying load balancing to n-tier application services (database)

Application Gateway

OSI Layer 7 application
Application Delivery Controller (ADC) as a service
SSL offload
Has Web Application Firewall (WAF)

Traffic Manager

DNS-level
Geographical load balancing
Offers different routing methods