Which tool is primarily used to implement rate limiting on network traffic?

The primary tool used to implement rate limiting on network traffic is a firewall. Firewalls are designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. Among their numerous features, firewalls can enforce rate limiting, which restricts the number of requests a user or device can make to a particular service over a specific time frame. This helps to mitigate denial-of-service attacks, manage bandwidth, and improve overall network performance by preventing any single source from consuming excessive resources.

Other tools like routers and proxy servers can also apply rate limiting, but their primary functions differ from that of a firewall. Routers typically focus on directing data packets between networks and ensuring efficient routing, while proxy servers function as intermediaries that facilitate requests and responses between clients and external servers. Network balancers primarily distribute traffic across multiple servers to optimize resource use and ensure availability, rather than enforcing specific rate limits on traffic. Thus, among these options, firewalls are uniquely equipped to implement rate limiting effectively.