Which network functionality controls the amount of traffic sent or received as well as the number of API requests within a specified period?

Rate limiting is the correct choice for controlling the amount of traffic sent or received as well as managing the number of API requests within a specified period. This functionality ensures that a system does not become overwhelmed by too many requests in a given timeframe, which can lead to performance degradation or service outages. By implementing rate limiting, organizations can maintain stability and efficiency, protect backend resources, and enforce usage policies across application interfaces.

This technique is particularly useful for APIs as it helps to manage how often a user can make requests. It not only enhances the overall user experience by preventing throttling but also protects against abuse, such as DDoS attacks, where malicious actors may send a large number of requests to overwhelm a service. By setting limits on requests, developers can ensure fair usage and reliability of the service for all users.

Bandwidth allocation, while related to the management of traffic, refers more to the distribution of network capacity rather than the control of request rates. Access control involves managing permissions and user access to resources, but it does not regulate how frequently those resources can be accessed. Filtering deals with sorting or blocking traffic based on certain criteria but does not inherently manage the volume of requests over time.