How does a proxy server determine user access?

A proxy server determines user access primarily by evaluating client IP address permissions. This involves checking the IP addresses of incoming requests against predefined access control lists (ACLs) or policies that dictate which IPs are permitted to access specific resources. This method is an efficient way for the proxy to manage access without requiring credentials or analyzing the content of the traffic.

Using client IP addresses allows the proxy server to make quick decisions regarding access based on who is attempting to connect. If an IP address is on the approved list, the request is allowed through; if not, the access is denied. This approach is especially useful in environments where users are coming from known locations, allowing for a straightforward and speedy access management system.

The other options relate to methods that are not typically the primary means by which a proxy server controls access. Checking user credentials against a database is more aligned with authentication methods, while analyzing network traffic pertains to monitoring and performance rather than access control. Measuring data transfer speeds does not directly relate to access determination; rather, it often pertains to network performance assessment.