The correct answer is A. Historically, before modern Zero Trust models were adopted, the normal way to connect a user to an application or service was to place both within a shared network context. This did not always require the exact same subnet, but it did require some level of common routable network connectivity. Legacy architectures assumed that once the user was on the trusted network, or extended into it through technologies such as VPN, they could reach the destination across that network.

Zero Trust architecture changes this assumption. Zscaler's architectural guidance emphasizes that users should gain access to applications without sharing network context or routing domain with those applications. That is one of the most important distinctions between legacy network-centric security and Zero Trust. The user no longer needs broad network reachability just to get to a specific service. Option B is too narrow because shared access historically did not always mean the same subnet. Options C and D are clearly incorrect. Therefore, the best answer is that initiators and destinations historically shared a network, because legacy connectivity depended on routed network access rather than identity-based, per-application brokerage.