1. 查看报错信息

systemctl restart named		服务一直起不来，查看报错信息是端口被占用了

2. 检查被占用的端口

 ps aux | grep named		检查端口信息

3. 杀死占用端口的进程后重启服务

kill -9 7854			强制杀死进程

systemctl restart named