What is the primary purpose of a firewall in a network?

The primary purpose of a firewall in a network is to protect the resources of that network by controlling the incoming and outgoing traffic based on predetermined security rules. This protective measure helps to prevent unauthorized access and potential cyber threats, thereby ensuring that sensitive data and internal resources remain secure. Firewalls can be implemented in both hardware and software forms, and their ability to block or permit traffic helps prevent malicious activities, such as hacking or the spread of malware.

The other options relate to different aspects of computer operations. For example, the description of managing user interfaces pertains more to user experience components rather than security measures. Real-time data processing is more aligned with operational systems and applications that handle dynamic data, while optimizing code performance is associated with programming best practices and software efficiency. Each of these plays a critical role in computing but does not specifically address the fundamental security function that a firewall provides.