Ubuntu系解决DNS查询慢与解析故障 Jun 25th 2018 Words: 262
This post is created 4 years ago, the content may be outdated.

在使用repo sync同步源码过程中，经常性出现如下错误：

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fatal: unable to access 'https://github.com/omnirom/android_bootable_recovery/': Could not resolve host: github.com
fatal: unable to access 'https://github.com/omnirom/android_external_fuse/': Could not resolve host: github.com
fatal: unable to access 'https://github.com/omnirom/android_bootable_recovery/': Could not resolve host: github.com
fatal: unable to access 'https://github.com/omnirom/android_external_fuse/': Could not resolve host: github.com

已知问题与路由DNS设置无关，通过ping与nslookup命令得到以下结果：

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[email protected] ~ $ nslookup github.com
Server:		127.0.1.1
Address:	127.0.1.1#53

Non-authoritative answer:
Name:	github.com
Address: 52.74.223.119
Name:	github.com
Address: 13.229.188.59
Name:	github.com
Address: 13.250.177.223

[email protected] ~ $ ping github.com
ping: unknown host github.com

其中nslookup的返回时间大概是10s，远超过超时阈值。由Server一栏可以得知Ubuntu系默认使用本地dnsmasq缓存查询。
精力有限，咱不对dnsmasq的故障进行深究，直接通过以下方式关闭dnsmasq。

编辑器打开/etc/NetworkManager/NetworkManager.conf。

将dns=dnsmasq注释掉，并sudo systemctl restart network-manager重启网络。

查看/etc/resolve.conf，确保DHCP给出的DNS在列表中。

完成配置。