dhcp无法启动

# DHCP Server Configuration file.
# see /usr/share/doc/dhcp*/dhcpd.conf.sample
#
ddns-update-style interim;
ignore client-updates;

subnet 192.168.10.0 netmask 255.255.255.0 {

# --- default gateway
option routers 192.168.10.121;
option subnet-mask 255.255.255.0;

option nis-domain "its-test.com";
option domain-name "its-test.com";
option domain-name-servers 192.168.10.121;

option time-offset -18000; # Eastern Standard Time
# option ntp-servers 192.168.1.1;
# option netbios-name-servers 192.168.1.1;
# --- Selects point-to-point node (default is hybrid). Don't change this unless
# -- you understand Netbios very well
# option netbios-node-type 2;

range dynamic-bootp 192.168.1.240 192.168.1.250;
default-lease-time 21600;
max-lease-time 43200;

# we want the nameserver to appear at a fixed address
host ns {
next-server ITS-Linux;
hardware ethernet 00:0C:29:6A:08:39;
fixed-address 192.168.10.121;
}
}

我是在Vm中安装的RHEL5，安装了dhcpd，并且配置文件如上。
dhcp服务器的IP为本机IP192.168.10.121。
还是无法启动dhcp服务，不知道还是配置问题还是其他问题？

谢谢