What version of KML is served using ArcGIS Server?
The header of a KML network link document being served from ArcGIS will indicate that the content is KML 2.2. However, the tags within the KML will only be those that were defined in the KML 2.0/2.1 specifications. Some key items supported in served KML network links include geometry (points, lines, polygons), ground overlays, feature symbology, LookAt positions, screen overlays (map legends), radio button folders (map legend placements), folders (group layers), HTML descriptions, and regions. Examples of KML items not supported in served KML network links include COLLADA and time spans (animations).