What is the purpose of a firewall?

The purpose of a firewall is to filter incoming and outgoing traffic, which is why this answer is the most appropriate. Firewalls act as a security barrier between a trusted internal network and untrusted external networks, such as the internet. They monitor and control the flow of network traffic based on predetermined security rules. By filtering traffic, firewalls help to block unauthorized access and protect networks from various threats, including malware and hacking attempts. This capability is essential for maintaining the integrity and confidentiality of sensitive data and ensuring that only legitimate traffic is allowed to enter or leave the network.

In contrast, analyzing network speed pertains to performance measurement, which is not a function of a firewall. Connecting different networks involves routers or switches, which handle data traffic and facilitate communication between disparate networks. Enhancing wireless coverage is a task typically managed by access points and extenders rather than firewalls, which are focused on security and traffic management. Thus, the role of filtering traffic stands out as the defining function of a firewall.