C) This is a primary function of a proxy server. When a device on a private network sends a request to a server on the internet, the proxy server intercepts the request. The proxy server then forwards the request using its own public IP address, making it appear as if the request originated from the proxy server itself. This effectively hides the internal network's IP addresses, enhancing security and privacy.
A) suggests that the proxy would automatically discard all traffic that does not match a specific content pattern, but this describes a more specialized (and stricter) form of content filtering or firewall behavior rather than a straightforward proxy function. While some proxies can implement content filtering or other security measures, it is not their primary or most common role to automatically discard all unmatched traffic.
B) While proxy servers can work in conjunction with encryption protocols (like HTTPS), their main role isn't to provide end-to-end encryption. Encryption is handled by protocols like TLS/SSL. A VPN is more focused on this function.
D) Mentions inspecting every packet at the data-link layer (OSI Layer 2) for intrusion prevention. Most proxies work at higher layers (most commonly the application layer, Layer 7), since their purpose is to intercept requests, possibly modify or log them, and forward them on behalf of clients. Inspecting traffic at Layer 2 belongs more to network-based intrusion detection/prevention systems or layer 2 firewalls that work deep in the network stack, not to proxies that primarily handle requests and responses at the application (or sometimes transport) layer.