When designing a network virtual appliance (NVA) solution in active-active high availability (HA) mode for traffic inspection between Azure subnets, the Microsoft Azure Load Balancer Standard SKU is the recommended option.
According to the Microsoft Azure Administrator Guide (Implement and Manage Load Balancing and Network Security) and official documentation ("Azure Load Balancer HA Ports Overview" and "Deploy highly available NVAs in Azure"), the following configurations are required:
* Deploy a Standard Load Balancer (Option E):The Standard Load Balancer supports advanced high- availability features, including HA Ports, multiple front-end IPs, floating IP, and zone redundancy.The Basic SKU does not support HA Ports or multiple frontends, which are essential for this active-active scenario.
* Add a Frontend IP Configuration, Backend Pool, and Health Probe (Option C):The load balancer requires:
* A Frontend IP configuration that defines the incoming traffic address.
* A Backend pool containing the two NVAs.
* A Health probe to continuously check the operational state of each NVA, enabling automatic failover if one becomes unhealthy.This ensures uninterrupted traffic flow and compliance with the "automatic failover" requirement.
* Add Two Load Balancing Rules with HA Ports and Floating IP Enabled (Option D):
* HA Ports allow the load balancer to handle traffic on all ports for a specific frontend configuration, supporting multiple services (two in this case) without defining individual port rules.
* Floating IP (Direct Server Return) must be enabled to allow the NVAs to participate in an active- active configuration. Floating IP ensures that the return traffic bypasses the load balancer, essential for symmetric routing and consistent session handling across multiple NVAs.Disabling Floating IP would result in asymmetric flows and failed connections during failover.
Together, these three configurations meet the requirements for automatic failover, active-active NVA operation, and load balancing across multiple services with distinct IP addresses.
Azure Documentation Reference Summary (Extracted from Microsoft Learn and AZ-104 Study Guides):
* "Standard Load Balancer supports high availability using HA Ports, enabling all-port traffic load balancing."
* "For active-active NVAs, configure floating IP for both load balancing rules."
* "A frontend IP, backend pool, and health probe are mandatory for any load balancer deployment."
* "Basic Load Balancer does not support HA Ports or multiple frontend configurations." Final Verified Answer: # C, D, and E
* C. Add a frontend IP configuration, a backend pool, and a health probe.
* D. Add two load balancing rules that have HA Ports and Floating IP enabled.
* E. Deploy a Standard Load Balancer.