CentOS 7 NetworkManager Keeps Overwriting /etc/resolv.conf

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Mattias Geniar, September 01, 2015

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In CentOS or Red Hat Enterprise Linux (RHEL) 7, you can find your /etc/resolv.conf file, which holds all nameserver configurations for your server, to be overwritten by the NetworkManager.

If you check the content of /etc/resolv.conf, it may look like this.

$ cat /etc/resolv.conf
# Generated by NetworkManager
search mydomain.tld
nameserver 8.8.8.8

The NetworkManager will assume it has the rights to control /etc/resolv.conf, if it finds a DNS related configuration in your interface configuration file.

$ grep DNS /etc/sysconfig/network-scripts/ifcfg-*
DNS1="8.8.8.8"
IPV6_PEERDNS="yes"

To prevent Network Manager to overwrite your resolv.conf changes, remove the DNS1, DNS2, … lines from /etc/sysconfig/network-scripts/ifcfg-*.

Now, you can manually change the /etc/resolv.conf file again, and you should be good to go. NetworkManager will no longer overwrite your DNS nameserver configurations.



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