The question involves Acme Corp experiencing performance degradation due to overutilized uplinks from ToR-1 to Core-1 and Core-2, with a diagram (not provided) indicating a potential MSTP (Multiple Spanning Tree Protocol) issue. The task is to identify valid reasons for uplink overutilization.

Analysis of Options:

Option A:Incorrect. Incorrect root bridge configuration (e.g., Core-2 as root) may cause suboptimal paths but is not directly linked to uplink overutilization without further context.

Option B:Correct. Inconsistent VLAN-to-instance mappings across switches can cause MSTP to block unexpected ports, funneling traffic through fewer uplinks and causing overutilization.

Option C:Incorrect. Firmware mismatches may cause compatibility issues but are unlikely to directly cause uplink overutilization.

Option D:Correct. Using the default MSTP region configuration (e.g., default region name and revision) across switches can lead to all switches forming a single MSTP region, potentially causing suboptimal topology and uplink overuse.

Option E:Incorrect. Running MSTP with admin-network port-type on uplinks and downlinks is not a standard cause of overutilization; it’s a specific port role.

Why B and D are Correct:MSTP relies on consistent region configurations (region name, revision number, VLAN-to-instance mappings) to create efficient topologies. If VLAN-to-instance mappings differ (Option B), switches treat each other as separate regions, leading to blocked ports and traffic concentration on fewer uplinks, causing overutilization. Similarly, using the default MSTP region configuration (Option D) without customizing the region name or revision can result in all switches forming a single region with suboptimal spanning tree instances, potentially overloading specific uplinks. Both issues disrupt MSTP’s ability to balance traffic across redundant paths, aligning with HPE Aruba Networking’s MSTP troubleshooting scenarios.

Relevance to Certification Objectives:

Network Resiliency and Virtualization (8%):Troubleshooting MSTP for redundancy and fault tolerance.

Switching (19%):Diagnosing Layer 2 issues, including MSTP misconfigurations.

Performance Optimization (6%):Remediating uplink utilization issues.