361

Is there a command to list dns servers used by my system?

I tried

$ 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 127.0.0.1
$ cat /etc/network/interfaces 
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

But it doesn't list any servers, if I go to "Network Manager GUI Tool", in Wireless section it lists "DNS 192.168.1.1 8.8.8.8 8.8.4.4"

Can I get same information from command line?

I am using Ubuntu 12.04 LTS

5
  • What are you trying to find? the DNS servers being used by your system? or are you trying to do a DNS lookup?
    – Thomas Ward
    Jun 18, 2012 at 14:42
  • The former @LordofTime
    – ish
    Jun 18, 2012 at 15:16
  • @LordofTime DNS servers being used by my system Jun 18, 2012 at 15:19
  • you are using 127.0.0.1. are you running a DNS server?
    – Skaperen
    Aug 19, 2015 at 10:18
  • See unix.stackexchange.com/q/28941/38647 for a non-Ubuntu version of this question
    – mwfearnley
    Jun 11, 2018 at 12:41

12 Answers 12

333

resolv.conf isn't really used anymore, unless you implement it yourself. The network manager does it now. I created an alias to list the DNS servers on my system, as I sometimes switch from OpenDNS to Google's open DNS.

Ubuntu >= 15

nmcli device show <interfacename> | grep IP4.DNS

Ubuntu <= 14

nmcli dev list iface <interfacename> | grep IP4

In my case, <interfacename> is eth0, which is common, but not always the case.

See if this is what you want.

EDIT:

I think resolv.conf is actually used indirectly, because the network manager creates the server that listens on 127.0.0.1, but I was told that this is an implementation detail that should not be counted on. I think that if you enter DNS addresses before this entry, they might get used, but I'm not sure exactly how this works. I think it's best to use the network manager in most cases, when possible.

18
  • 3
    thanks, yes that seems to be working, ubuntu networking seems to be confusing, so I can set dns servers in resolve.conf/base or in /etc/network/interfaces or in network manager, is there a definitive guide for ubuntu networking? Jun 18, 2012 at 15:26
  • 1
    stgraber.org/2012/02/24/dns-in-ubuntu-12-04 is a nice article abount DNS resolution in ubuntu 12.04 Jun 18, 2012 at 15:37
  • 6
    I'm using 15.04 and 'nmcli dev show |grep DNS' works for me instead.
    – flickerfly
    Aug 11, 2015 at 18:37
  • 2
    @vcardillo: the original question stated: "I am using Ubuntu 12.04 LTS". It's been 5 years since I posted my answer. Nothing lasts forever. May 22, 2017 at 23:17
  • 1
    I would like to warn readers that the information provided by nmcli and nm-tool might not be correct. In testing my router setup, I changed the DHCP server to configure a DNS. On my client (linux mint 17.3) I did sudo dhclient -r; sudo dhclient to renew IP configuration. At this point both commands I mentioned showed the old DNS, not the new one. cat /etc/resolv.conf did work for me, but according to op it did not work for him. The only reliable way to figure out which DNS is used appears to be to a lookup with for example dig, but I doubt dig will show you all configured DNS. Sep 11, 2019 at 21:32
150

In Ubuntu 18.04 and 20.04 you can use systemd-resolve --status

4
  • 2
    NB if you cat /etc/resolv.conf it even says this
    – Rqomey
    Sep 6, 2019 at 13:16
  • 1
    On 21.04 it says sd_bus_open_system: No such file or directory Sep 26, 2021 at 13:17
  • 1
    IMO this should be the accepted answer. Also, it's worth pointing out that systemd-resolve mydomain.com outputs which DNS server exactly is being queried (very useful if e.g. you have set up a VPN and so on).
    – balu
    Oct 12, 2021 at 16:01
  • 2
    This is not a full answer as it does not explain what the command returns.
    – foki
    Nov 9, 2021 at 0:10
88

This is valid for Ubuntu 13.10 and earlier. For Ubuntu 14.04 and above, see Koala Yeung's answer to: How to know what DNS am I using in Ubuntu from 14.04 onwards


Use

nm-tool

You will get an output similar to

NetworkManager Tool

State: connected (global)

- Device: eth0  [Wired connection 1] -------------------------------------------
  Type:              Wired
  Driver:            e1000e
  State:             connected
  Default:           yes
  HW Address:        00:11:22:33:44:55

  Capabilities:
    Carrier Detect:  yes
    Speed:           1000 Mb/s

  Wired Properties
    Carrier:         on

  IPv4 Settings:
    Address:         10.21.6.13
    Prefix:          24 (255.255.255.0)
    Gateway:         10.21.6.1

    DNS:             10.22.5.133
    DNS:             10.22.5.3

Or to see just the DNS do

nm-tool | grep DNS
8
  • 1
    just wanted to add-up, going to nm-applet's connection information menu will also work :)
    – Samik
    Jun 18, 2012 at 15:26
  • 1
    +1 this also works, as does nm-cli as answered by @Marty Fried Jun 18, 2012 at 15:30
  • 2
    works great on lubuntu 14.04 as well. thanks Oct 21, 2015 at 13:50
  • 2
    nm-tool is not found on 15.10
    – labyrinth
    Nov 24, 2015 at 17:16
  • 1
    yeah this doesn't work anymore... no nm-tool in 16.x either. nmcli (in Marty Fried's answer) is the way to go
    – Lambart
    Feb 15, 2017 at 0:30
73

The two top-scoring answers, nmcli dev list iface <interfacename> | grep IP4 and nm-tool both assume that network-manager is in control. Which it is - on desktop machines most of the time at least. But the fuller answer is that sometimes network-manager is not in control. E.g. vpnc messes with /etc/resolv.conf directly.

So: First check if 127.0.0.1/localhost is used. This could be done with dig:

> dig something.unknown  | grep SERVER:
;; SERVER: 127.0.0.1#53(127.0.0.1)

Now you know that we are using localhost. Go ahead with one of the popular answers. I like:

> nm-tool | grep DNS:
    DNS:             8.8.8.8

But if 127.0.0.1/localhost is not used, then nm-tool's and nmcli's output will be misleading:

> dig something.unknown  | grep SERVER:
;; SERVER: 172.22.216.251#53(172.22.216.251)
> nm-tool | grep DNS:
    DNS:             8.8.8.8

Here, dig is correct and nm-tool's information is misleading. In reality addresses local to the environment I've VPN-ed into are resolved correctly. All of which Google's DNS 8.8.8.8 doesn't know about.

This is because after connecting to a VPN with vpnc, it puts a line in /etc/resolv.conf so it looks like:

# 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 1.2.3.4
nameserver 127.0.0.1
search MyDomain
4
  • 5
    This is the most complete answer
    – Marinos An
    Jul 4, 2018 at 13:17
  • Thank you. Some of us out here do not use NM and that is good for the community. Sep 9, 2018 at 12:27
  • Just for completion, the dig utility can be easily installed with apt install dnsutils. Jul 24, 2019 at 7:47
  • though you just need dig | grep SERVER: ... dig will give you the root DNS if you pass no address
    – baradhili
    May 15 at 4:13
37

cat /etc/resolv.conf should show your DNS servers.

You may not modify the resolv.conf directly with Ubuntu 12.04. If you need to change them though, you can add new DNS servers in your /etc/network/interfaces file by adding the following:

 dns-nameservers x.x.x.x x.x.x.x

where x is the DNS servers you wish to use.

If I were you, I would uninstall network-manager. In my opinion it's a pile of crap.

You can accomplish everything you need to do manually without worrying about changing your settings, especially if you have multiple NICs on the computer.

3
  • 2
    Do I have to restart nm after doing the dns change? Mar 25, 2015 at 7:43
  • 1
    --Thanks. This is great. It works even without that network-manager business.
    – Adam
    Jul 18, 2015 at 8:23
  • "cat /etc/resolv.conf should show your DNS servers". It doesn't.
    – Marinos An
    Jul 4, 2018 at 13:14
14

nmcli version 0.9.10

You can use either of these commands:

nmcli -t -f IP4.DNS device show eth0
IP4.DNS[1]:192.168.1.1
IP4.DNS[2]:8.8.8.8

nmcli -t -f IP4.DNS connection show conn-name
IP4.DNS[1]:192.168.1.1
IP4.DNS[2]:8.8.8.8
3

Amazing how many ways there are to do it. On an Ubuntu Server 18.04, if you don't want to install anything extra like nm-tool, then systemd-resolve --status will work out of the box for DNS information.

If you're interested getting not only your DNS servers, but also default gateway, IP address, network mask, etc, then netplan ip leases eth0 will give you all that information in an easy-to-read form (assuming you're interested in the eth0 interface).

1
  • Thank you, I didn't have NetworkManager and didn't want to install it, your answer was very helpful. Apr 14, 2020 at 12:49
3

On Ubuntu 20.04

systemd-resolve --status | grep -B 9 -A 6 "Current DNS Server"

gave me a clear result as to what DNS was in use for each adapter using DNS.

To reconfigure DNS

man systemd-resolved

reveals the DNS servers contacted are determined by global settings in /etc/systemd/resolved.conf.

Sudo edit that file and uncomment and set DNS= and FallbackDNS= to the IPv4 DNS servers you want. For example, DNS=8.8.8.8 and FallbackDNS=8.8.4.4 would use Google Public DNS. Restart the machine to apply the change.

@PLA, thank you for this answer which led me down this path.

2

In Ubuntu 15.10 you can get DNS

nmcli device show <interface name> 
1

On systems where systemd-resolved is NOT installed :

$ host -v something.unknown | awk -F "[ #]" '/Received /{print$5}' | uniq
192.168.1.1

On systems where NetworkManager is running :

$ ( nmcli -f IP4.DNS,IP6.DNS dev list || nmcli -f IP4.DNS,IP6.DNS dev show ) 2>/dev/null | awk '/DNS/{print$NF}'
192.168.1.1
1

In Ubuntu 20.04, if your resolve.conf points to loopback:

$ sudo cat /run/systemd/resolve/resolv.conf
nameserver 127.0.0.53
options edns0 trust-ad

and:

$ ss -plnt | grep ':53'
LISTEN   0        4096            127.0.0.53%lo:53               0.0.0.0:*    

you can use resolvectl to show status for interfaces:

$ resolvectl status

Global
LLMNR setting: no                  
MulticastDNS setting: no                  
  DNSOverTLS setting: no                  
      DNSSEC setting: no                  
    DNSSEC supported: no                  
          DNSSEC NTA: 10.in-addr.arpa
....

Link 4 (wlo1)
      Current Scopes: DNS           
DefaultRoute setting: yes           
       LLMNR setting: yes           
MulticastDNS setting: no            
  DNSOverTLS setting: no            
      DNSSEC setting: no            
    DNSSEC supported: no            
  Current DNS Server: 10.128.128.128
         DNS Servers: 10.128.128.128
          DNS Domain: ~.
0

Seems to be managed by network manager. Have a look here http://manpages.ubuntu.com/manpages/precise/man5/NetworkManager.conf.5.html

for a large explanation.

Or the short version it to look in

 /etc/NetworkManager/NetworkManager.conf

or

 <SYSCONFDIR>/NetworkManager/NetworkManager.conf
1
  • 5
    but /etc/NetworkManager/NetworkManager.conf doesn't have any dns servers listed in it Jun 18, 2012 at 15:20

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