The most resolution of the Viewsonic VT2406 is 480i. That's 56% less resolution than a 1080i PC screen, which is the most frequently found resolution. 1080i is also found on this PC monitor. This LCD screen also have 1080p and 480p and 720p video modes.
This LCD screen's resolution (480i) is in fact the worst resolution amongst all PC monitors of this age and spec.
A 2160p video mode is the best resolution amongst similar types of LCD screen.