Zero Trust, Segmentation, and Service-to-Service Security Questions

Designing network and service-communication trust models where no implicit trust is granted by network location. Covers zero-trust access, microsegmentation and identity-aware perimeters, least-privilege network access, lateral-movement prevention, and segmenting environments to contain blast radius, together with securing service-to-service communication in distributed and microservices architectures: mutual authentication between services, service mesh security, multi-tenancy isolation, east-west traffic, and the security implications of scale and geographic distribution. The architectural trust-boundary pattern and its enforcement across decomposed, high-scale systems, distinct from device-level firewall configuration.