Function of the Collapsed Core Layer in a Two-Tier Architecture

A.

In a two-tier network architecture, the collapsed core layer functions to aggregate traffic from the access layer and route it towards the distribution layer, which in turn connects to the WAN and other external networks. The collapsed core layer is sometimes referred to as the backbone layer.

Option A: Enforcing routing policies The collapsed core layer is responsible for performing routing functions such as enforcing routing policies. Routing policies define how traffic is handled as it traverses the network. They can be used to direct traffic based on various criteria such as source, destination, protocol, or port number.

Option B: Marking interesting traffic for data policies The marking of interesting traffic for data policies is usually performed at the access layer, where traffic is initially received from end devices. The collapsed core layer does not typically perform this function.

Option C: Applying security policies Security policies can be applied at various levels within the network architecture, including the collapsed core layer. The collapsed core layer can act as a gateway between different security zones, and as such, can enforce policies that restrict access between them.

Option D: Attaching users to the edge of the network The access layer is responsible for connecting end-user devices to the network. The collapsed core layer does not typically perform this function.

In conclusion, the function performed by the collapsed core layer in a two-tier architecture is to aggregate traffic from the access layer and route it towards the distribution layer, as well as enforce routing and security policies. Therefore, option A and C are both correct answers.