Please clarify regarding the various NFS issues.

Like,

1 - user unable to get/see the filesystem/directory which is exported by server. (NOTE-user is having write authentication)
2 - how to rectify the NFS server is not responding ...
3 - how to rectify the mount issue.
(NOTE-The nfsd, mountd and portmap daemons are running...

Thanks in advance.

These issues have various possible causes .. we're here to help with specific problems, please use an internet search engine for generic information.

On your NFS server, look at the syslog:
while you are trying to access the share. NFS produces useful messages. Usually the problem is something non-obvious like the portmapper not being allowed for NFS.

jlinkels

1 - user unable to get/see the filesystem/directory which is exported by server. (NOTE-user is having write authentication)
2 - how to rectify the NFS server is not responding ...
3 - how to rectify the mount issue.
(NOTE-The nfsd, mountd and portmap daemons are running...

First tell us, which command did you run at the client side to see the directories exported by the server ?
At Server side, try running commands
#exportfs -v (for verbose)
#exportfs -r (refresh)
What are they showing ?

CLient side command
#showmount -e "server ip"

For the answer of your 2nd doubt,
try starting Portmap service first then start NFS service.

for 3rd doubt, what problem exactly you are facing while mounting ?