Question

The directive in a Dockerfile that instantiated containers will listen on the indicated port at launch.

A) EXPOSE
B) LISTEN
C) OPEN
D) PORT

Answer 1

The Dockerfile directive that indicates which ports a container listens on at launch is the EXPOSE directive.

Step-by-step explanation:

The directive in a Dockerfile that instantiated containers will listen on the indicated port at launch is A) EXPOSE. The EXPOSE directive is used to inform Docker that the container listens on the specified network ports at runtime. Docker uses this information to determine which ports to expose to the host when running the container.

It does not actually publish the port but serves as a way of documenting which ports are intended to be published. To actually publish the port when running the container, you need to use the -p flag with docker run.