CentOS更新DHCP版本，若用的是DHCP服務器軟件（isc-dhcp-server），可參考以下方法：
cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.bak，cp -r /var/lib/dhcp /var/lib/dhcp.bak。sudo yum update。sudo yum upgrade dhcp 或 sudo yum install dhcp。sudo systemctl restart dhcpd。dhcpd -v。yum list available dhcp查找可用版本。wget http://mirror.centos.org/centos/7/os/x86_64/Packages/dhcp-4.4.1-40.el7.x86_64.rpm。sudo yum localinstall dhcp-<版本號>.rpm。若更新的是DHCP客戶端（dhclient），可參考：
cp /etc/dhcp/dhclient.conf /etc/dhcp/dhclient.conf.bak。sudo yum update。sudo yum install -y dhcp（包含dhclient）。sudo systemctl restart network。dhclient -v。
