Thousands of air-quality devices post a curl-based REST payload every minute to a single-region backend using Premium Tier. You want to minimize daily average TTFB. How should you build the backend and network?

The correct option uses an external Application Load Balancer (ALB) with a managed instance group (MIG). An ALB operates at Layer 7, providing advanced features like HTTP(S) routing and SSL termination, which are crucial for REST payloads and can optimize connection handling, thereby minimizing Time To First Byte (TTFB). MIGs ensure high availability and scalability for the backend. The other options are less optimal: Compute Engine VMs with Cloud DNS policies (weighted or simple round-robin) provide basic load balancing but lack the advanced Layer 7 features of an ALB, which are more effective for HTTP-based traffic. An external passthrough Network Load Balancer operates at Layer 4, offering high performance but without the HTTP-specific optimizations an ALB provides for REST traffic, which would be less effective at minimizing TTFB for this use case.