[CentOS] service nfs start hangs on CentOS 4

Hello when I try to start nfs the command hangs.
I have found out, that the problem is, that I set an IP address at 
/etc/exports
sample:
/var/foo XXX.XXX.XXX(some rights)
when replace the IP address to * then service nfs start work, but no one 
can use the exports.
What goes wrong??
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