Darmstadt University of Applied Sciences Darmstadt University of Applied Sciences Darmstadt University of Applied Sciences Darmstadt University of Applied Sciences Darmstadt University of Applied Sciences Quantum communication modules connected via a link, either via fiber or free-space communications, have been used since a while to distribute random numbers as secure keys, but there are other use cases, such as time synchronization. By today, a number of research and industrial efforts are underway to built complete networks, primary for secure key distribution, i.e., so-called Quantum Key Distribution Networks (QKDN). This memo briefly explores the space of QKDNs and identifies spots of potentials interest to develop standardized protocols specific for such networks.