CEVAP:

Epistemology is a concept about how we come to know about these existing things (that ontology is interested in) and their reality. So, epistemology is interested in investigating the sources of our knowledge of reality. And,  epistemology is also interested in investigating whether we are in a state to know reality as it exits independent of us (reality as is); and whether what we are able to know corresponds to a reality that exists independent of us (independent of us knowing it).