====== Add DNS Server ====== Jan 2017 ---- Normally we just add the IP Address, Subnet Mask and Gateway to the ifcfg-eth0 file, as that is all we need. But if it is required that we need to update the OS, or add a piece of software (htop for example) then we may need to add the DNS settings. \\ \\ While this was written with CentOs 6/7 in mind, it may work for other Linux distributions. \\ \\ There are two ways this can be done. \\ \\ ---- ==== Method 1 ==== \\ Use "PEERDNS=no". This option will prevent /etc/resolv.conf from being modified by a DHCP server. So instead of using DHCP-provided DNS, you can specify any arbitrary DNS servers you want to use in /etc/resolv.conf. \\ \\ The configuration file for your network interface (e.g., eth0) looks like the following. \\ \\ **//sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0//** \\ \\ DEVICE=eth0\\ BOOTPROTO=dhcp\\ ONBOOT=yes\\ **PEERDNS=no**\\ \\ \\ Then, add static DNS to /etc/resolv.conf \\ \\ **//sudo vi /etc/resolv.conf//** \\ \\ nameserver 8.8.8.8\\ nameserver 8.8.4.4\\ \\ \\ ---- ==== Method 2 ==== \\ Alternatively, you can specify DNS servers directly in the interface configuration file, instead of modifying /etc/resolv.conf yourself. That is: \\ \\ **//sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0//** \\ \\ DEVICE=eth0\\ BOOTPROTO=dhcp\\ ONBOOT=yes\\ **DNS1=8.8.8.8**\\ **DNS2=8.8.4.4**\\ \\ \\ The DNS servers specified with "DNS1/DNS2" directives will then automatically be added to **/etc/resolv.conf** when the interface is activated. So there is no need to modify **/etc/resolv.conf** yourself.