问题详情：
操作系统：centos7.6
root@oraclelinux ~]# ping www.baidu.coom
ping: www.baidu.coom: Name or service not known
[root@oraclelinux ~]# ping
ping: : Name or service not known
[root@oraclelinux ~]# ping www.baidu.coom
ping: www.baidu.coom: Name or service not known
[root@oraclelinux ~]# ping 192.168.8.1
connect: Network is unreachable
[root@oraclelinux ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See “systemctl status network.service” and “journalctl -xe” for details.
查网卡状态，发下无静态ip信息
[root@oraclelinux ~]# ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 301 bytes 18577 (18.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 301 bytes 18577 (18.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:40:19:db txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
查网络服务状态
[root@oraclelinux ~]# systemctl status network.service
● network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network; bad; vendor preset: disabled)
Active: failed (Result: exit-code) since Tue -09-03 21:01:31 CST; 15s ago
Docs: man:systemd-sysv-generator(8)
Process: 8806 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
Sep 03 21:01:31 oraclelinux network[8806]: RTNETLINK answers: File exists
Sep 03 21:01:31 oraclelinux network[8806]: RTNETLINK answers: File exists
Sep 03 21:01:31 oraclelinux network[8806]: RTNETLINK answers: File exists
Sep 03 21:01:31 oraclelinux network[8806]: RTNETLINK answers: File exists
Sep 03 21:01:31 oraclelinux systemd-sysctl[8961]: Line is not an assignment in file…)
Sep 03 21:01:31 oraclelinux systemd-sysctl[8961]: Line is not an assignment in file…)
Sep 03 21:01:31 oraclelinux systemd[1]: network.service: control process exited, c…=1
Sep 03 21:01:31 oraclelinux systemd[1]: Failed to start LSB: Bring up/down networking.
Sep 03 21:01:31 oraclelinux systemd[1]: Unit network.service entered failed state.
Sep 03 21:01:31 oraclelinux systemd[1]: network.service failed.
Hint: Some lines were ellipsized, use -l to show in full.
处理办法
link/ether 52:54:00:40:19:db brd ff:ff:ff:ff:ff:ff
[root@oraclelinux ~]# systemctl stop NetworkManager—关闭
[root@oraclelinux ~]# systemctl disable NetworkManager—禁止开机启动
[root@oraclelinux ~]# systemctl restart network
[root@oraclelinux ~]# ifconfig 网卡信息显示并状态正常
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.8.135 netmask 255.255.255.0 broadcast 192.168.8.255
inet6 fe80::20c:29ff:fe34:e5c0 prefixlen 64 scopeid 0x20
ether 00:0c:29:34:e5:c0 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 22 bytes 3372 (3.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 821 bytes 50077 (48.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 821 bytes 50077 (48.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:40:19:db txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
