CNR
Communications and Networking Riser
COMx
Communication Port (x = port number)
CPU
Central Processing Unit
CRT
Cathode-Ray Tube
DAC
Discretionary Access Control
DB-25
Serial Communications D-shell connector, 25 pins
DB-9
9-pin D-shell connector
DC
Direct Current
DDOS
Distributed Denial of Service
DDR
Double Data-Rate