Final answer:
A compression gasket is typically used to seal the connection between a shower drain and DWV piping, providing a watertight seal that withstands pipe movements.
Step-by-step explanation:
When connecting a shower drain to a DWV (drain, waste, and vent) system, the typical sealant used is a compression gasket. This gasket is designed to fit between the drain's flange and the DWV piping, ensuring a watertight connection that prevents leaks. Unlike cement or caulking, a compression gasket can be tightened sufficiently and can tolerate slight movements or expansions in the piping without breaking the seal. Flashing is typically used for weatherproofing exterior joints, which is not the case in shower drain installations.