In the centos8 system, the original time synchronization service NTP/ntpdate service is no longer available. Install it using Yum and the prompt no longer exists
Previous versions: Yum install – y NTP
centos8：yum -y install chrony
At this time, the temporary synchronization time method is: chronyd – Q ‘server NTP ntsc. ac.cn iburst’
Suddenly, I found that the time of a machine was a few minutes slow. Before, ntpd service was not set up. At present, ntpdate plus timing task is used for time synchronization. The following errors are reported when directly executing ntpdate:
# ntpdate cn.pool.ntp.org Exiting, name server cannot be used: Temporary failure in name resolution (-3) 3 Sep 15:46:46 ntpdate[13742]: name server cannot be used: Temporary failure in name resolution (-3)
Generally, the error is temporary failure in name resolution, which cannot be resolved, and the Ping test is also unsuccessful. Therefore, it is judged that there is a problem with the resolv.conf file
# ping www.baidu.com ping: unknown host www.baidu.com
You can fill in the correct DNS address according to the network provider
# cat /etc/resolv.conf nameserver 114.114.114.114 nameserver 8.8.8.8 # ntpdate cn.pool.ntp.org 3 Sep 17:54:33 ntpdate[17314]: step time server 5.103.139.163 offset 995.587830 sec
Can’t find host ntp1.aliyun.com: servname not supported for AI_ socktype (-8)
Error reported:
[root@web01 ~]# ntpdate ntp1.aliyun.com
Error resolving ntp1.aliyun.com: Servname not supported for ai_socktype (-8)
11 Feb 20:58:03 ntpdate[3318]: Can't find host ntp1.aliyun.com: Servname not supported for ai_socktype (-8)
11 Feb 20:58:03 ntpdate[3318]: no servers can be used, exitingReason: the domain name resolution error is caused by the change or nonexistence of the/etc/services file
[root@web01 etc]# ls -l servic*
-rw-r--r--. 1 root root 10240 Feb 11 02:27 services
-rw-r--r-- 1 root root 641020 Feb 11 02:22 services.bak Long format comparison reveals that the source file has been changed
[root@web01 etc]# mv services /tmp
[root@web01 etc]# ls -l servic*
-rw-r--r-- 1 root root 641020 Feb 11 02:22 services.bak
[root@web01 etc]# mv services.bak services
[root@web01 etc]# ls -l servic*
-rw-r--r-- 1 root root 641020 Feb 11 02:22 services
[root@web01 etc]# ntpdate ntp1.aliyun.com
12 Feb 17:00:54 ntpdate[3363]: step time server 182.92.12.11 offset 71111.641937 sec