In order to export /usr and /bin via NFSv4, /exports was created and contains working...

mount-tnfsv4 server://mnt

of an NFC-Client, it is observed that /mnt contains the content of the server’s /usr directory instead of the content of the NFSv4 foot folder.

Which option in /etc/exports has to be changed or removed in order to make the NFSv4 root folder appear when mounting the highest level of the server? (Specify ONLY the option name without any values or parameters.)

Answer:  fsid

The fsid option in /etc/exports is used to specify a unique identifier for each exported filesystem. For NFSv4, there is a distinguished filesystem which is the root of all exported filesystems, and it is specified with fsid=root or fsid=0, both of which mean the same thing. If this option is used for the /exports directory, then it will be the root of the NFSv4 hierarchy, and any subdirectories under it will be mounted relative to it. This means that when mounting the highest level of the server, the client will see the content of /exports instead of the NFSv4 root folder. To avoid this, the fsid option should be removed or changed to a different value for the /exports directory, so that it is not the NFSv4 root. The other options in /etc/exports are not relevant for this question.