Final answer:
Spanning Tree Protocol (STP) is required for redundant links between Layer 2 switches and removing single points of failure with multiple Layer 2 switches to ensure correct network operation.
Step-by-step explanation:
The two network design features that require Spanning Tree Protocol (STP) to ensure correct network operation are redundant links between Layer 2 switches and removing single points of failure with multiple Layer 2 switches.
When there are redundant links between Layer 2 switches, STP helps to prevent loops in the network by blocking some redundant links while keeping one active. This prevents broadcast storms and other network issues.
Similarly, when single points of failure are removed with multiple Layer 2 switches, STP ensures that only one switch is active at a time, allowing for redundancy in case one switch fails.