I get back the collection of layers with their names and ids, but the 'name' that is returned is actually the layer alias, and therefore it's possible for several layers in a map service to have the same name. Is there any REST call that would allow me to verify the fully qualified layer name?
It doesn't look like it but I could be wrong. For a workaround you could add your FQLN to the layer's description. Then lookup the information on all layers that match that alias you were searching for and check in the description contains the FQLN you want.