单项选择题

某Linux DHCP服务器dhcpd.conf的配置文件如下：
ddns-update-style none；
subnet 192.168.0.0 netmask 255.255.255.0
range 192.168.0.200 192.168.0.254;
ignore client-updates;
default-lease-time 3600;
max-lease-time 7200;
option routers 192.168.0.1;
option domain-name"test.org";
option domain-name-servers 192.168.0.2;
host test1 hardware ethernet 00:E0:4C:70:33:65；fixed-addresS 192.168.0.8;
客户端IP地址的默认租用期为______小时。