A user is unable to connect from one workstation to another workstation.

Afirewallcan block traffic between workstations if it's not properly configured. If a user cannot connect from one device to another on the network, it is likely that the firewall settings are preventing this communication.

“Firewalls control the incoming and outgoing network traffic based on predetermined security rules. If improperly configured, they may block legitimate access between devices.” — CompTIA ITF+ Study Guide

Other options:

B. Database – Not related to connectivity

C. Anti-malware – Protects from malicious software, not network configuration

D. Certificate – Used for secure communication, but not basic connectivity

Correct answer: A