If the display is analog, the DVI connection will convert the digital signal to an analog signal, otherwise no conversion will be necessary. It is worth mentioning that, the analog video bandwidth of DVI is higher than VGA, thus higher resolution can be supported compared to VGA.
So, it can be applied by high resolution displays such as UXGA and HDTV. DVI cables or ports with fewer pins are designed for lower resolution devices. In order to support maximum resolution, the DVI port should contain all the pins.