ESRI ArcGIS API for Javascript Query and Select Sample - Feature Layers

[MichaelVolz]

To All Javascript API Developers:

From what I am reading in the samples, the queries appear to be constructed against a feature layer.  Is there a particular reason why this would be the case?

Could it be that is makes it easier to deal with 1 layer of a mapservice that can be composed of multiple layers?

Can you even perform queries against a dynamic mapservice?

[KenBuja]

Of the many samples that use Query, several (like this, this, and this)https://developers.arcgis.com/javascript/jssamples/query_showinfowindow.html use it on a dynamic map service.