why does certbot still can generate my certs after wipe?

i tested some things in docker and f*d up, also removed all containers and volumes including the certbot ones. so why is certbot still able to give me my certificates back? is it because they are stored somewhere in a web storage? is it because dockers storage driver keeps files even after deleting volumes/containers? is it because letsencrypt only needs a succesful DNS challenge and nothing more? i'm just curious how it works.. --- Addressing comments: > What do you mean by "give ... certificates back"? Are you sure it's not just generating a new certificate? with "give certs back" my thinking was, that i actually would need more than just my mail and dns possession. does this imply i don't need to back up the letsencrypt certificates and instead create new ones? what is the minimum requirement to "overwrite" then? thanks for help