Regularly updating software and firmware in network devices is essential to fix security vulnerabilities and bugs that could be exploited by attackers. These updates often include patches and fixes to address newly discovered vulnerabilities, reducing the risk of security breaches and data loss.

The Certificate Authority (CA) is responsible for managing digital certificates in a Public Key Infrastructure (PKI) system. It issues, revokes, and manages digital certificates, verifying the identity of entities in a network and ensuring secure communication through encryption.

Placing a firewall between the router and the internal network is the most secure location because it allows the firewall to filter both incoming and outgoing traffic, protecting the internal network from external threats while also providing control over outgoing traffic.

Two-factor authentication (2FA) should be implemented whenever employees work remotely or access sensitive data to add an extra layer of security beyond just passwords. It helps mitigate the risk of unauthorized access, especially when accessing critical systems from outside the corporate network.

A subnet mask is used to divide an IP address into network and host portions. It determines which part of the IP address represents the network ID and which part represents the host ID, allowing routers to determine the destination network for data forwarding.