A systems administrator needs to open the DNS TCP port on a Linux system from...

Firewall configuration is a key topic in the Security domain of CompTIA Linux+ V8. DNS primarily uses UDP port 53, but TCP port 53 is also required for zone transfers, large responses, and certain reliability scenarios. In this case, the administrator explicitly needs to allow DNS over TCP from a specific network.

The correct command is ufw allow 53/tcp from 10.0.0.0/24. This rule allows incoming TCP traffic on port 53 only from the specified subnet, following the principle of least privilege. Linux+ V8 documentation emphasizes restricting firewall rules by source network whenever possible to minimize attack surfaces.

Option A is incorrect because UFW service aliases like dns are not always guaranteed to map explicitly to TCP, and the syntax is incomplete. Option B is invalid because ufw enable is used to enable the firewall globally and does not define rules. Option D disables firewall protections and introduces a major security risk.

Linux+ V8 best practices stress precise, minimal firewall rules instead of broad or disabling actions. Therefore, C is the correct and secure choice.