What are the signs that network-centric zero trust is not keeping up?

When network-centric zero trust falls behind

The clearest sign is that the control model still assumes a stable internal perimeter while the environment has already moved to cloud services, remote access, and workload-to-workload traffic. When policy mostly follows subnets, VPN entry points, or static network location, zero trust is no longer shaping access at the point where decisions are actually made.

That gap usually shows up as repeated exceptions, brittle segment rules, and manual approvals that exist only to keep legacy network thinking working. The programme may still reduce risk, but it is no longer keeping pace with how trust should be expressed in modern identity-centric environments.

What the control model is failing to express

Network-centric zero trust starts to lag when it treats network position as the main proxy for trust, instead of continuously evaluating the requesting user, workload, device, and context. In practice, that means the architecture is no longer aligned to NIST SP 800-207 Zero Trust Architecture, which expects explicit verification, least privilege, and policy decisions that are not anchored to location alone.

A second sign is that the trust boundary becomes hard to explain in operational terms. If teams can describe east-west segmentation but cannot describe why a given request is allowed, what identity state was checked, or what policy was evaluated at decision time, the design has drifted away from the zero trust intent.

This is where identity, access, and workload trust become the real test. Modern access paths often depend on service-to-service credentials, short-lived tokens, or attested workload identity, so a network boundary by itself cannot capture who or what is actually requesting access. That is why identity-oriented zero trust guidance such as the Zero Trust Identity Guide and Guide to SPIFFE and SPIRE matter when the programme needs to move beyond perimeter logic.

Operational signals that the design is getting stale

Look for growth in compensating controls that exist because the trust model is too coarse. Repeated firewall exceptions for SaaS, cloud, or partner traffic, broad internal allowlists, and special routes for “trusted” locations all suggest the programme is preserving old network assumptions rather than enforcing per-request policy.

Another sign is that lifecycle changes do not meaningfully alter access. If terminated users, decommissioned workloads, expired tokens, or moved services still retain effective access until a network rule is manually updated, the control plane is lagging behind the identity plane. That is exactly the kind of lifecycle gap a broader identity governance view would surface, as reflected in IAM and IGA Basics and Ultimate Guide to NHIs.

A third signal is visibility drift. When logs show flows permitted by segment or VPN path, but cannot answer whether the access was appropriate for the identity, the context, or the workload’s current state, the organisation is operating on coarse network trust rather than continuous verification. At that point, the architecture may still be secure in places, but it is no longer the right abstraction for the environment.

Risk and Threat Considerations

When zero trust is expressed mainly as network segmentation, the main risk is that attackers only need to win the same trust assumptions that defenders still rely on. Once an internal segment, remote access tunnel, or broadly trusted cloud path is treated as sufficient, lateral movement and privilege abuse become easier to hide inside “allowed” traffic.

Failure mechanism: Static trust boundaries allow access to persist after the identity, device, workload, or business context has changed, so compromised accounts or workloads keep more reach than they should.

Impact: The result is a wider blast radius, slower containment, and more manual exception handling during incidents, especially where cloud and SaaS access no longer fits the original network design.

Practitioner Guidance

What to verify: Test whether access decisions are made from identity, context, and policy at request time, or whether the network is still the primary trust signal. If the answer depends on where the request comes from more than who or what is making it, the model needs rework.

Common mistake: Treating microsegmentation, VPN replacement, or ZTNA adoption as proof that zero trust is mature. Those are delivery mechanisms; the more important question is whether policy remains valid when a user changes role, a workload moves, or a secret is rotated.

Practitioner takeaway: The programme is behind when you must explain trust with a boundary diagram instead of a live policy decision, because that means the control still reflects the network that once existed rather than the identities that exist now.

Related resources from NHI Mgmt Group

• What are the signs that an ICAM programme is not keeping up with Zero Trust?
• Why do non-human identities complicate zero trust architecture?
• Why do non-human identities increase zero trust risk?
• Why do NHIs complicate zero trust and least privilege efforts?