ArcGISTiledMapServiceLayer
http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer
ArcGISDynamicMapServiceLayer
http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Population_World/MapServer
ArcGISTiledMapServiceLayer
http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer
ArcGISDynamicMapServiceLayer
http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Population_World/MapServer