Question: what is d sub port used for?
Answer: When used as a monitor interface, a D-Sub port is also known as a VGA port, an analog connection standard that's been around for some time. The connector is a DE-15 connector with 15 pins in three rows, often referred to as a "mini-D-Sub 15-pin" or "D-Sub 15-pin" connector. (Some connectors omit unused pins.)