If I run sudo apt-get update inside docker image and run it as a container, do I still need to sudo apt-get update on the machine too? I'm still trying to wrap my head around how exactly Docker works because one part of my brain is telling me that everything running in the Docker container relies on everything inside the Docker container itself so it's not necessary to sudo apt-get update on the machine too and another part of my brain is telling me that's not right so I'm pretty confused now.