Choose Y here if you want to allow other computers to access
files residing on this system using Sun's Network File System
protocol. To compile the NFS server support as a module,
choose M here: the module will be called nfsd.

You may choose to use a user-space NFS server instead, in which
case you can choose N here.

To export local file systems using NFS, you also need to install
user space programs which can be found in the Linux nfs-utils
package, available from http://linux-nfs.org/. More detail about
the Linux NFS server implementation is available via the
exports(5) man page.

Below you can choose which versions of the NFS protocol are
available to clients mounting the NFS server on this system.
Support for NFS version 3 (RFC 1813) is always available when
CONFIG_NFSD is selected.

If unsure, say N.

source code:

fs/nfsd/