If a line is too short to hold even one dash sequence, AutoCAD LT draws a continuous line between the endpoints, as shown below.
You can accommodate short segments by using a smaller value for their individual linetype scales. For more information, see Controlling Linetype Scale.
For polylines, you can specify whether a linetype pattern is centered on each segment or is across vertices throughout the entire length of the polyline. You do this by setting the PLINEGEN system variable.