Sketcher > Sketcher Diagnostic Tools > To Detect Open Ends of Entities
  
To Detect Open Ends of Entities
Use the Highlight Open Ends diagnostic tool to highlight the end points of entities that do not coincide with end points of other entities in an active sketch or an active sketch group. In 3D sketch geometry only the open ends of valid entities are highlighted.
 
* Open ends of construction geometry are not highlighted.
Open end points of entities are highlighted by default. To hide the endpoints for any new sketches during the session, perform one of these operations:
Click Sketch > Highlight Open Ends.
Set the sketcher_highlight_open_ends configuration option to no.