Final answer:
Cyber Systems Operations is the 3D AFS that focuses on the administration of servers and server farms throughout Air Force installations worldwide.
Step-by-step explanation:
The 3D Air Force Specialty (AFS) that focuses on the administration of servers and server farms throughout Air Force installations worldwide is Cyber Systems Operations. This AFS is responsible for managing network infrastructure, ensuring servers are properly configured and maintained, and troubleshooting the server-related issues.