求教：在REDHAT5.3下怎样配置时间服务？

我在REDHAT ENTERPRISE 5.3上的NTP.CONF文件如下：
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
#restrict default kod nomodify notrap nopeer noquery
#restrict -6 default kod nomodify notrap nopeer noquery
#server otherntp.research.gov
#server ntp.research.gov
#restrict default nomodify noquery notrap
restrict 202.112.10.60
restrict 202.106.199.36
restrict 202.112.7.150
restrict 127.0.0.1 mask 255.0.0.0
restrict 10.10.0.0 mask 255.255.0.0 nomodify notrap
#restrict ntp.research.gov mask 255.255.255.255 nomodify notrap noquery
#restrict otherntp.research.gov mask 255.255.255.255 nomodify notrap noquery

# Permit all access over the loopback interface. This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict -6 ::1


# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.rhel.pool.ntp.org
#server 1.rhel.pool.ntp.org
#server 2.rhel.pool.ntp.org
server time.buptnet.edu.cn
server s1b.time.edu.cn
server s1c.time.edu.cn
server s1d.time.edu.cn

#broadcast 192.168.1.255 key 42 # broadcast server
#broadcastclient # broadcast client
#broadcast 224.0.1.1 key 42 # multicast server
#multicastclient 224.0.1.1 # multicast client
#manycastserver 239.255.254.254 # manycast server
#manycastclient 239.255.254.254 key 42 # manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available.
#server 127.127.1.0 # local clock
#fudge 127.127.1.0 stratum 10

server 202.112.10.60 prefer
server 202.106.199.36
server 202.112.7.150
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10

# Drift file. Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42


但在客户端上显示
[root@w]# ntpdate 10.10.0.133
24 Apr 15:16:14 ntpdate[6372]: no server suitable for synchronization foun

不知道为什么，请高手指点，谢谢