Cisco Certified Network Professional 2025 – 400 Free Practice Questions to Pass the Exam

Common Spanning Tree (CST) is specifically designed to support a single Spanning Tree Protocol (STP) instance across all VLANs on a network. This means that regardless of the number of VLANs configured in the network, CST views them as a single entity and makes its decisions based on the overall topology of the network.

In this scenario, when multiple VLANs are present, CST does not differentiate between them; there is one path to each network segment, and it calculates the optimal path to prevent loops based on the entire spanning tree instance. As a result, all traffic from different VLANs shares the same spanning tree, which can sometimes lead to inefficiencies in load balancing and performance.

The other choices reflect features or behaviors that do not apply to CST. For instance, the option that refers to multiple spanning trees for load balancing relates more to Multiple Spanning Tree Protocol (MSTP) or Rapid Spanning Tree Protocol (RSTP), which allow for more efficient use of links by supporting load balancing across multiple VLANs. The reference to proprietary protocols is not indicative of CST's operation, which is standardized. Lastly, the mention of utilizing multiple VLAN instances relates to protocols that manage spanning trees differently than CST does.