Fix "NFS mount error: Bad superblock (or) Unable to mount I/O error"

The other day while trying to mount one of my NFS server on the client machine I was getting this error. Well it took me time to figure out the solution but in the ended it ended out to be a very easy one.
Bad superblock (or) Unable to mount I/O error
This happens generally because the local portmap service is stopped on the server or the client machine so make sure this service is up and running properly in both the machines
# service portmap start
NOTE: In Red Hat 6 portmap service is termed as rpcbind
# service rpcbind start