ro: specifies that the directory may only be mounted as read only
rw: grants both read and write permissions on the directory
no_root_squash: is an extremely dangerous option that allows remote “root” users the same privilege as the “root” user of the host machine
subtree_check: specifies that, in the case of a directory is exported instead of an entire filesystem, the host should verify the location of files and directories on the host filesystem
no_subtree_check: specifies that the host should not check the location of the files being accessed withing the host filesystem
sync: this just ensures that the host keeps any changes uploaded to the shared directory in sync
async: ignores synchronization checks in favor of increased speed