True or False: In a flat network, all systems are in scope if any single system stores, processes, or transmits account data.

In a flat network environment, all systems are connected without segmentation or sufficient controls to isolate sensitive data. If any single system in this type of network stores, processes, or transmits account data, it poses a risk to the security of all connected systems. This is because unauthorized access to one system could allow an attacker to reach others, increasing the likelihood of sensitive data exposure. Consequently, all systems in the flat network become in scope for compliance with PCI DSS requirements, as they could potentially access cardholder data directly or unintentionally.

In contrast, a segmented or properly controlled network would limit PCI DSS scope to only those systems that handle sensitive cardholder information, which would not be the case in a flat network.