Difference between Proxy Server and NAT (network address translation)

Explain the purpose and features of a proxy server

A proxy server is an application layer service that functions as an intermediary for network clients accessing the Internet. Proxy servers protect the clients by preventing direct connections between them and Internet servers, and they also enable administrators to monitor and regulate users’ Internet access.

Like a network address translation (NAT) router, a proxy server receives requests from clients on a private network and forwards those requests to the destination on the Internet, by using its own registered address to identify itself. The primary difference between a proxy server and a NAT router is that the proxy server interposes additional functions into the forwarding process. These functions can include the following:

• Filtering Administrators can configure proxy servers to limit user access to the Internet by filtering out requests sent to undesirable sites.
• Logging A proxy server can maintain logs of user Internet activity for later evaluation and reporting.
• Caching A proxy server can store frequently accessed Internet data in a local cache, which it can then use to satisfy subsequent requests for the same data at higher speeds.
• Scanning A proxy server can scan incoming data from the Internet for various types of malware and outgoing data for confidential company information.

Unlike a NAT router, which is invisible to the workstation, a proxy server requires that applications be configured to use it—a process that can be manual or automatic.

True or false: Proxy servers are hardware devices that connect to router or switch ports.

Answer: False. Proxy servers are software products that you install and run on a computer with a registered IP address.

TIP

EXAM TIP Network+ exam candidates should able to distinguish between a proxy server and a NAT router, both of which are designed to protect a private network from Internet intruders. For more information on NAT, see Objective 2.1: Given a scenario, install and configure routers and switches.

True or false: A proxy server must be designed for a specific version of a specific application, which is why they are usually made by the same company as the applications they service.

Answer: False. Proxy servers are designed to serve specific applications, based on the port numbers they use for their communications. Therefore, they are not designed for specific application versions, nor are they typically made by the application manufacturers.

CompTIA® Network+® Rapid Review (Exam N10-005)