While editing a list item in the subsite, the map makes an HTTP request to a geometry service (http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer) even if is not mentioned in the list of pre-configured geometry services. This prevents ArcGIS Mapping for SharePoint v2.0 and v2.1 being used in environments without external connections to the internet.