The recommended color scheme for a no-entry zone is:

The recommended color scheme for a no-entry zone is red and white. This combination is widely recognized as a warning sign that indicates danger and restricts access. The color red specifically conveys a sense of urgency and alertness, prompting individuals to take immediate action or avoid the area altogether. The addition of white enhances visibility and makes the warning more distinct.

In the context of safety protocols, the red and white scheme aligns with established safety standards and regulations, which aim to ensure clear communication about hazards. This scheme is designed not only to catch the attention of individuals but also to convey the seriousness of the situation, making it an effective choice for marking off areas where entry is prohibited due to risks involved.