417

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 the Wireless section it lists "DNS 192.168.1.1 8.8.8.8 8.8.4.4".

Can I get the same information from the command line?

I am using Ubuntu 12.04 LTS.

Matthias Braun
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Anurag Uniyal
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14 Answers14

380

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. You can see your interfaces with

nmcli device status

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.

Niko Fohr
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Marty Fried
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253

In Ubuntu 18.04 and 20.04 you can use systemd-resolve --status. In newer versions use resolvectl status.

Paweł Prażak
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PLA
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89

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
JamesThomasMoon
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tgm4883
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80

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
Peter V. Mørch
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39

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.

Adam
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ssc
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20

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: ~.
Zanna
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Marek-A-
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13

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
iman
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10

Since Ubuntu 20.04, you can use resolvectl which has been already mentioned. But I would like to highlight the dns which is a little bit more clean compared to status, see

resolvectl dns

$ resolvectl dns
Global:
Link 2 (ens34): 8.8.8.8
Link 3 (docker0):

resolvectl [status]

$ resolvectl 
Global
       Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub

Link 2 (ens34)
    Current Scopes: DNS
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 8.8.8.8
       DNS Servers: 8.8.8.8
        DNS Domain: company.com


Link 3 (docker0)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Murmel
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5

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).

Phil
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4

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.

SpeedCoder5
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4

In Ubuntu 15.10 you can get DNS

nmcli device show <interface name>
Suleman Hasib
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2

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
SebMa
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1

Many of the posts here have two problems:

  1. They provide only an answer for Ubuntu Desktop systems that employ NetworkManger out of the box
  2. Provide false information of checking /etc/resolv.conf

First of all, Stop checking or editing /etc/resolv.conf on current Ubuntu systems. Ubuntu is deeply embedded in systemd. This means ntp, hostnames, services, and DNS are being supported by systemd services. You will noticed that /etc/resolv.conf will only have one address 127.0.0.53 which is yourself, mainly talking to systemd dns services. Dont change this file, stop looking at it, stop messing with it.

How to check Ubuntu Desktop DNS settings and status:

  • As @iman pointed out You can check settings from nmcli:
ip -br a 
# Make note of interface name
nmcli -t -f IP4.DNS device show $interface_name

How to check Ubuntu SERVER DNS settings and status:

  • You can check settings from the netplan conf file
cat /etc/netplan/00-installer-config.yaml

How to check status of DNS on Ubuntu Desktop and Ubuntu Server:

  • You can check status of DNS with this command
systemd-resolve --status --no-pager | grep "DNS Servers" -A 2

Note the above is only to list the number of dns servers if there are only two. If you want all of the DNS servers (a variable ammount) use this

systemd-resolve --status | awk '{ for(i=1;i<=NF;i++) if($i~/^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$/) print $i }'
Dave
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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
mbs
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