Configure DNS manually

papilon · 03-15-2019, 06:21 PM

Hi Guys,

How do we configure DNS manually on Ubuntu? I thought to edit /etc/resolv.conf but the file says not to configure/edit it (in old days we used to edit it but now this file is auto-generated).

I also came across some fake info like "Changes should be made in /etc/sysconfig/network"

link to fake info, which is in comments: https://www.cyberciti.biz/tips/linux...ns-client.html

No such folder like sysconfig. So how do we configure DNS manually?

PS
I already configured IP address by ip command, I added routing too. Now I need to configure DNS service.

thx

dc.901 · 03-15-2019, 06:30 PM

You should review this: https://help.ubuntu.com/lts/servergu...ration.html.en

Quote:

To configure your system to use static address assignment, create a netplan configuration in the file /etc/netplan/99_config.yaml.

There is also an example on the page...

Or, perhaps this page: https://help.ubuntu.com/16.04/ubuntu...net-wired.html

JJJCR · 03-16-2019, 01:16 AM

Just my 2 cents, it would depend if your network config is DHCP or Static.

If it is DHCP then it will be Auto Generated.

Check out this link: https://unix.stackexchange.com/quest...-12-04-lts-gui

From above link to check for DHCP:

Quote:

Other method is cat /var/log/syslog and check for some thing like below

DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 6
DHCPOFFER from 10.100.1.254
DHCPREQUEST on eth0 to 255.255.255.255 port 67
DHCPACK from 10.100.1.254

or try this: journalctl | grep DHCP

agillator · 03-16-2019, 01:41 AM

It is not difficult if you know what dns servers you want to use (up to three).

Code:

sudo cp /etc/resolv.conf /etc/resolv.conf.bak
sudo rm /etc/resolv.conf

With whatever text editor you like, create a new /etc/resolv.conf with up to three lines of

Code:

nameserver xxx.xxx.xxx.xxx

using the addresses of the nameservers you want to use, of course.
Then, and this is absolutely necessary,

Code:

sudo chattr -e /etc/resolv.conf
sudo chattr +i /etc/resolv.conf

This locks the file so it cannot be changed, even by the system. Now you should be using the dns servers you wish. If it doesn't seem to take, reboot and it should.
Note: to do ANYTHING with resolv.conf now you must first

Code:

sudo chattr -i /etc/resolv.conf

To return to the system resolv.conf simply change the attribute as above and move the backup file back.