Explain Zero Trust network architecture principles.

Zero Trust eliminates implicit trust based on network location. Principles: verify explicitly (always authenticate/authorize), least privilege access, assume breach. Implementation: strong identity (MFA), device health verification, microsegmentation (granular access controls), encrypted communications (mTLS everywhere), continuous monitoring. Technologies: BeyondCorp, ZTNA products, identity-aware proxy. Replaces perimeter-based security (VPN/firewall). Challenge: retrofitting legacy applications, identity management complexity. Essential for cloud-native, remote work.