Why have traditional networks relied on implicit trust to connect initiators to workloads?

The correct answer is B . Traditional networks have historically relied on implicit trust because the foundational model of TCP/IP networking is built to enable connectivity , not to establish trust or least-privileged access. Once a user or device is on the network, routing and addressing make it possible to reach other resources unless additional controls are layered on top. This is exactly the legacy pattern that Zero Trust seeks to replace.

Zscaler’s Universal ZTNA guidance explains that legacy approaches connected users to applications by placing them in the same network context or routing domain , whereas Zero Trust decouples the user from the network and allows access only to approved applications. The architecture specifically states that users should access applications without sharing network context with them and that granular, context-based policy should control access instead of implicit network trust.

So the underlying reason is architectural: traditional networking protocols were optimized for reachability and communication, not identity-based trust decisions. That is why implicit trust became common, and why Zero Trust is such a significant shift away from the old model.