Here's a link to the documentation on this: KML—Help | ArcGIS
AGOL caches KML's for up to 30 minutes.
One way to get around that is to make another KML file and use the <NetworkLink> Tags in it (an example can be found here). Even though the KML is at http://dotp.blob.core.windows.net/511/511events.kml, we reference the kml where the actual data is at (http://dotp.blob.core.windows.net/511/511_events_data.kml) and specify a refresh interval in seconds (600 = 10 min).
Google's KML Reference guide is a GREAT place to go and look for details on KML markup tags.
Hope this helps answer your question.
David Runneals
GIS Intern, Iowa Department of Transportation
Thanks David! That works well for me and it just may be the solution that we use to begin to incorporate these dynamic kml layers in our web maps.
The only thing I see that is unfortunate about this method is that the actual kml layers are embedded deeper into the service if you need to go deeper to turn particular layers on of off. But that's a relatively small consequence in this case.
Heath
Yup, NP. Please mark my response answered if that is what you needed.
I also have posted about that same issue here. Hopefully someone will be able to answer it eventually.
-David
I don't think I can mark this as answered since I am not the person who started this thread. At least that's how it used to be in the old forums...
Thanks again.