NFS exports not working

[Dave Martini 1]

Hi all, I have a RHEL 2.1 AS machine that is exporting the following:

exportfs -v
/u01/app/dbafast/files
                <world>(rw,async,wdelay,root_squash)
/u10/app/dbafast/files
                <world>(rw,async,wdelay,root_squash)
/u11/app/dbafast/files
                <world>(rw,async,wdelay,root_squash)

Here's the /etc/exports file on the serer

more /etc/exports
/u01/app/dbafast/files *(rw)
/u10/app/dbafast/files *(rw)
/u11/app/dbafast/files *(rw)

Here's the df -k on the server
df -k
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/sda3             37452628  22247840  13302292  63% /
/dev/sda1                46636     23061     21167  53% /boot
/dev/sdb1            961195208  74787448 837581812   9% /u10
/dev/sdc1            961195208  27656524 884712736   4% /u11
none                   1029376         0   1029376   0% /dev/shm

Here's showmount from the client


I can mount /u10 and /u11 and /u01 from a RHEL 3.0 WS client but can
only do an ls on /u10 and /u11. I can cd into /u01 but when
I type ls it just sits there and does not list any files within it
and I have to control C out. The only difference is that /u10 and /u11
are separate volumes on separate disks and /u01 is part of /. Not sure
if this is the cause. I can mount /u01 and do ls on it just fine
on Solaris machines but not on Linux. 
I can't showmount from the linux client however to the server
showmount -e linuxnfsserver
showmount: can't get address for linuxnfsserver

Does RHEL 2.1 use nfs 2 or nfs 3? What about
RHEL 3.0? How can I check which version of NFS the machine is running and or
change it?
Any ideas would be great. 
David Martini
LLNL