- 不要直接手动修改文件 /etc/resolv.conf
安装好Ubuntu之后设置了静态IP地址，再重启后就无法解析域名。想重新设置一下DNS，打开/etc/resolv.conf
cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND — YOUR CHANGES WILL BE OVERWRITTEN
内容是一段警告：说这个文件是resolvconf程序动态创建的，不要直接手动编辑，修改将被覆盖。
root@Ubuntu14:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 100.100.2.138
nameserver 100.100.2.136
options timeout:2 attempts:3 rotate single-request-reopen
root@Ubuntu14:~#
ubuntu修改DNS有如下两种方法。
- 方法一：修改文件/etc/resolvconf/resolv.conf.d/base
root@Ubuntu14:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 100.100.2.138
nameserver 100.100.2.136
options timeout:2 attempts:3 rotate single-request-reopen
root@Ubuntu14:~# vim /etc/resolvconf/resolv.conf.d/base
root@Ubuntu14:~# cat !$
cat /etc/resolvconf/resolv.conf.d/base
nameserver 223.5.5.5
nameserver 223.6.6.6
root@Ubuntu14:~# resolvconf -u
root@Ubuntu14:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 100.100.2.138
nameserver 100.100.2.136
nameserver 223.5.5.5
options timeout:2 attempts:3 rotate single-request-reopen
root@Ubuntu14:~# nslookup www.baidu.com
Server: 100.100.2.138
Address: 100.100.2.138#53Non-authoritative answer:
www.baidu.com canonical name = www.a.shifen.com.
Name: www.a.shifen.com
Address: 220.181.112.244
Name: www.a.shifen.com
Address: 220.181.111.188root@Ubuntu14:~#
- 方法二：修改文件 /etc/network/interfaces
root@iZbp1b66g5htibj2m7yyv3Z:~# cat /etc/network/interfacesauto lo
iface lo inet loopbackauto eth0
iface eth0 inet dhcpdns-nameservers 223.5.5.5 # 在最后添加这一行
- 常用命令
linux刷新dns的缓存方法是： sudo /etc/init.d/nscd restart
最暴力的方法刷dns，重启网络： sudo /etc/init.d/networking restart
查看当前DNS解析情况：
nslookup www.baidu.com
dig | grep SERVER
root@iZbp1b66g5htibj2m7yyv3Z:~# /etc/init.d/nscd restart
* Restarting Name Service Cache Daemon nscd [ OK ]
root@iZbp1b66g5htibj2m7yyv3Z:~# /etc/init.d/networking restart
stop: Job failed while stopping
start: Job is already running: networking
root@iZbp1b66g5htibj2m7yyv3Z:~# dig |grep SERVER
;; SERVER: 100.100.2.138#53(100.100.2.138)
root@iZbp1b66g5htibj2m7yyv3Z:~# nslookup www.baidu.com
Server: 100.100.2.138
Address: 100.100.2.138#53Non-authoritative answer:
www.baidu.com canonical name = www.a.shifen.com.
Name: www.a.shifen.com
Address: 220.181.111.188
Name: www.a.shifen.com
Address: 220.181.112.244root@iZbp1b66g5htibj2m7yyv3Z:~#
- CoreOS修改DNS
1) vim /etc/resolv.conf
2) vim /etc/systemd/resolved.conf
3) systemctl restart systemd-resolved
4) reboot
coreos1 ~ # cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known DNS servers.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.nameserver 223.5.5.5
nameserver 223.6.6.6
search openstacklocal
coreos1 ~ # cat /etc/systemd/resolved.conf
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See resolved.conf(5) for details[Resolve]
DNS=223.5.5.5 223.6.6.6 # 用空格分隔多个dns
#FallbackDNS=
#Domains=
LLMNR=no # yes改为no
#DNSSEC=allow-downgrade
#Cache=yes
coreos1 ~ # systemctl restart systemd-resolved
coreos1 ~ # dig |grep SERVER
;; SERVER: 223.5.5.5#53(223.5.5.5)
coreos1 ~ # reboot
