Active Geo-Replication with an automatic failover group meets the strict RPO (<5 mins) and RTO (<30 mins) requirements. It provides asynchronous replication of transactions to a readable secondary in another region and enables fast, automated failover, making it the most appropriate and cost-effective solution for a critical application with these objectives. Manual failover or restore-from-backup options would not meet the aggressive RTO.

Azure App Service with Autoscale provides automatic, rules-based scaling for the web and API tiers, perfectly matching the unpredictable traffic spikes. The Hyperscale tier for Azure SQL Database offers independent scaling of compute and storage, capable of rapidly scaling to handle the database load from the front-end spikes. This PaaS-focused approach minimizes management overhead and optimizes costs through automatic scaling.

Azure Cosmos DB SQL API is the best fit. It’s designed for massive scale of JSON documents (IoT data) and provides rich querying capabilities with a SQL-like language. It can efficiently handle complex queries with filters on multiple properties. While Azure SQL Database can store JSON, it is not optimized for the same scale of document ingestion and flexible schema typical of IoT scenarios.

An Isolated App Service Plan (ASEv3) runs your App Service directly in your Azure Virtual Network. Creating a private endpoint for the Storage account places it on a private IP address within a subnet. Integrating this private endpoint with the ASE’s VNet allows the App Service to communicate with the Storage account entirely over the Microsoft backbone network, with no traffic traversing the public internet, thus fully complying with the policy.

Azure Cosmos DB is built for this exact scenario. Its turnkey global distribution feature automatically and transparently replicates data to any number of Azure regions with low latency. It provides read regions that can serve local users with single-digit millisecond reads, perfectly meeting the requirement for low-latency, read-only copies synchronized on a schedule (which can be near-real-time or batched).

A well-structured subscription and management group hierarchy is the foundational pillar of a secure Azure landing zone. It enables scalable management, delegated administration, targeted policy enforcement (like Azure Policy), and streamlined cost management. This structure must reflect the organization’s governance (e.g., platform vs. application teams, environments like prod/non-prod) and operational needs before detailed technical decisions are made.

Azure NetApp Files is the recommended service for enterprise-grade, high-performance shared file storage in Azure, especially for Linux-based HPC workloads. It provides a fully managed, highly available NFS service (among other protocols) that can deliver the low latency and high throughput required by hundreds of concurrent nodes accessing large files. While a custom NFS VM offers control, it introduces significant management overhead and single-point-of-failure concerns.

This is the canonical real-time analytics architecture on Azure. Event Hubs is optimized for massive-scale telemetry ingestion. Stream Analytics provides a SQL-like language for performing real-time aggregations and anomaly detection, with outputs to Power BI for live dashboards and to a data warehouse like Synapse Analytics for persistent storage and further historical/batch analysis. This combination is purpose-built for this scenario.

Virtual network peering is non-transitive. Peering SpokeA to Hub and SpokeB to Hub does not create connectivity between SpokeA and SpokeB. To enable direct communication, you must create a separate VNet peering connection directly between SpokeA and SpokeB. Using a hub firewall/NVA is an alternative (transitive routing), but the question asks for direct spoke-to-spoke traffic, which requires direct peering.

Active Geo-Replication with an automatic failover group meets the strict RPO (<5 mins) and RTO (<30 mins) requirements. It provides asynchronous replication of transactions to a readable secondary in another region and enables fast, automated failover, making it the most appropriate and cost-effective solution for a critical application with these objectives. Manual failover or restore-from-backup options would not meet the aggressive RTO.0