solaris 11 client nfs gone missing

Solaris 11 is all new all the time. One thing that's sort of annoying or mystifying is why, after booting, my zones just decide to skip out on the whole mounting of nfs exports even though they are defined in /etc/vfstab. That's okay. I don't mind creating a cron job:

if [ $(mount| grep 'nfsserver' | grep -v grep | wc -l | tr -s "\n") -eq 0 ]; then mount -a ; fi 2>&1

Oh, and I'm okay with running it every five minutes in crontab.

0,5,10,15,20,25,30,35,40,45,50,55 * * * * /root/scripts/script.sh