What Is Zero Trust? "Never Trust, Always Verify"
Zero Trust is a security model summed up as "never trust, always verify". It assumes no user or device is trustworthy by default — even inside the network — and verifies every access request. It replaces the outdated idea of a trusted "inside" behind a firewall.
Why the old model failed
The traditional "castle and moat" model trusted everything inside the perimeter. But once an attacker got in (via phishing, a stolen laptop, a compromised vendor), they roamed freely. Cloud, remote work and mobile devices erased the perimeter entirely — there's no clean "inside" any more.
Core principles
- Verify explicitly — authenticate and authorise every request (identity, device, location).
- Least privilege — give only the access needed, nothing more.
- Assume breach — segment and monitor as if an attacker is already inside.
Multi-factor authentication, micro-segmentation and continuous monitoring implement it — modern security direction worth knowing for interviews.
Frequently asked questions
What is zero trust in simple terms?
A model that trusts no user or device by default and verifies every access request, regardless of whether it comes from inside or outside the network.
Why is zero trust needed?
Cloud, remote work and mobile devices removed the network perimeter, so the old 'trust everything inside' model no longer protects anything.
What are the principles of zero trust?
Verify explicitly, enforce least-privilege access, and assume breach — segmenting and monitoring as if attackers are already inside.
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