Which traffic direction indicated by QRadar events and flows suggests that the network hierarchy does not have a well-defined network subnet?

The choice indicating that the network hierarchy does not have a well-defined network subnet is the R2R (Router to Router) traffic direction. When significant amounts of traffic or flows are observed moving directly between routers, it often suggests a lack of proper segmentation within the network. A well-defined subnet structure typically limits communication within specific boundaries, thus minimizing unnecessary inter-router traffic.

In a well-structured network, you would expect traffic to predominantly flow at specific layers, with clear demarcations between different segments of the network. For example, inbound traffic would be incoming from external sources to internal networks, while outbound traffic would usually flow from internal networks to the external internet. Local traffic is confined to devices within the same subnet and generally does not indicate broader network issues. In contrast, R2R traffic can imply that routers are handling significant amounts of intercommunication, often not constrained by well-defined subnets, which can lead to potential security and performance issues.