#exportfs -v
Exportfs command will show the content of file /etc/exports, the result will be something like this
/opt/ltsp/i386 192.168.0.0/255.255.255.0(ro,no_root_squash)
/var/opt/ltsp/swapfiles 192.168.0.0/255.255.255.0(rw,no_root_squash)
/home 192.168.0.0/255.255.255.0(rw,no_root_squash)
If the result is different, something like this :
[root@localhost etc]# exportfs -v
exportfs: could not open /var/lib/nfs/etab for locking
then check the file. If the file is error or the size is zero, you can delete it.
Restart NFS with these command :
service nfs restart
Make sure no error message displayed and boot again the client.