Centos7.6配置DHCP的Failover时，DHCP一直处于recovering状态，不分发地址！！

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主DHCP服务器配置:
文件dhcpd.conf
################
ddns-update-style none;
default-lease-time 720;
max-lease-time 100;
failover peer "dhcp"{
primary;
address 10.5.255.234;
port 520;
peer address 10.5.255.235;
port 519;
max-response-delay 60;
max-unacked-updates 10;
mclt 7200;
split 128;
load balance max seconds 3;

}

inculde "/etc/dhcp/dhcpd.master";
############################
备DHCP服务器配置:
文件dhcpd.conf
################
ddns-update-style none;
default-lease-time 720;
max-lease-time 100;
failover peer "dhcp"{
secondary;
address 10.5.255.235;
port 519;
peer address 10.5.255.234;
port 520;
max-response-delay 60;
max-unacked-updates 10;
load balance max seconds 3;

}

inculde "/etc/dhcp/dhcpd.master";
################################
dhcpd.master 里面就一个10.5.255.0/24的subnet
#############################
测试服务器间端口通信无问题！
############################
但是两台服务器一直处于recovering状态，不下发地址；异常如附件图

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