How to view the DNS address assigned by DHCP?

Question

ifconfig can not show it.

$ ifconfig -a
eth0      Link encap:Ethernet  HWaddr 90:e6:ba:22:6a:f2  
          inet addr:192.168.1.111  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::92e6:baff:fe22:6af2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:224856 errors:0 dropped:0 overruns:0 frame:0
          TX packets:220040 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:166848627 (166.8 MB)  TX bytes:20256333 (20.2 MB)
          Interrupt:46 Base address:0x4000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:5889 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5889 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:468885 (468.8 KB)  TX bytes:468885 (468.8 KB)

wlan0     Link encap:Ethernet  HWaddr 00:26:5e:e8:4f:8e  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

@david6 inet addr:192.168.1.111 Bcast:192.168.1.255 Mask:255.255.255.0 inet addr:127.0.0.1 Mask:255.0.0.0 — Victor S, Sep 22 '12 at 03:48
This should help you cat /var/lib/dhcp3/dhclient.leases | grep dhcp-server-identifier — devav2, Sep 22 '12 at 03:53
@devav2 $ cat /var/lib/dhcp/dhclient-529bed02-363e-4e97-bd5d-9f63f42f17f2-eth0.lease |grep dhcp-server-identifier option dhcp-server-identifier 192.168.1.1; option dhcp-server-identifier 192.168.1.1; option dhcp-server-identifier 192.168.1.1; option dhcp-server-identifier 192.168.1.1; option dhcp-server-identifier 192.168.1.1; — Victor S, Sep 22 '12 at 04:01
*What are asking for?* The DHCP service assigns an IP address from a pool (or range). A DNS server returns IP addresses for a hostname, domain, or mailbox (MX-record). Your ifconfig output looks normal .. — david6, Sep 22 '12 at 04:10
@david6 I want to get the DNS address used by current network connection. — Victor S, Sep 22 '12 at 04:17
IP address of DNS server(s)? See @Anwar's answer. Hostname? Something else? — david6, Sep 22 '12 at 04:39

score 56 · Accepted Answer · edited Sep 18 '19 at 06:53

56

For at least Ubuntu 15.10 onward (possibly also earlier versions) run in a terminal:

nmcli dev show eth0 | grep IP4

eth0 is the most common iface, but it could be eth1, eth2, etc.

For older versions use nmcli dev list iface eth0 | grep IP4.

edited Sep 18 '19 at 06:53

Pablo Bianchi

15,657

answered Sep 22 '12 at 04:26

Marty Fried

18,466

1

Awesome answer! Appreciate your sharing! I got it. – Victor S Sep 22 '12 at 04:42
Glad it helped. I found it when I wanted a way to get that info, then parse it to display on demand, as i had 3 different possible DNS servers (ISP, Google, and OpenDNS). – Marty Fried Sep 22 '12 at 15:40
8

As of 15.04, the command is nmcli dev show – Sergiy Kolodyazhnyy Jun 18 '15 at 22:06
3

With nmcli dev show eth0 (as on 15.04) it also works on Debian Buster. Thanks! – Luc Jul 31 '17 at 22:47
hey @SergiyKolodyazhnyy you should add an answer, your command is the best one! – Yandry Pozo Sep 17 '17 at 21:02
1

@YandryPozo Posted an answer, as requested :) – Sergiy Kolodyazhnyy Sep 17 '17 at 21:19
this throws argument list not understood – Douglas Gaskell Apr 28 '18 at 19:01
will not work without network-manager. – mestia Oct 08 '19 at 12:18
@mestia - Well, considering nmcli is a command-line tool which is used for controlling NetworkManager, that makes sense. – Marty Fried Oct 08 '19 at 17:11

Pablo Bianchi · Answer 2 · 2022-09-22T19:06:31.837

19

Now that Ubuntu (and Debian and almost all distros) use systemd (check with file /sbin/init) maybe the more elegant way to get this info is with:

systemd-resolve --status
# Or 
resolvectl dns

freedesktop.org docs
Arch Wiki: Use systemd-resolve --status where it says resolvectl (systemd-resolve is a symlink to resolvectl).
If you have problems with DNS subsystem I suggest removing resolvconf package. May conflicts with systemd-resolve.

edited Sep 22 '22 at 19:06

answered Sep 18 '19 at 07:00

Pablo Bianchi

15,657

1

The perfect answer for systems not running NetworkManager. Ubuntu 18.04, Ubuntu 19.10 – Ryan Jeremiah Freeman Sep 21 '19 at 21:10
It works in Raspbian too – riofly Nov 12 '19 at 09:19
2

Doesn't work in Buster. I get Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found. – Aenfa Jun 15 '22 at 20:56
@Aenfa Debian is out of scope, but maybe this helps – Pablo Bianchi Jun 15 '22 at 21:16

score 14 · Answer 3 · answered Sep 22 '12 at 16:11

14

$ nm-tool

will also list DNS Servers.

answered Sep 22 '12 at 16:11

dixoncx

390

1

+1 because this has been tested working up to 14.04 release. For 15.04 and newer release, use nmcli as suggested by the other answer instead. – Dec 04 '15 at 04:12

score 9 · Answer 4 · edited Sep 18 '19 at 07:04

9

To get the DNS address open terminal (Ctrl+Alt+T) and type:

cat /var/lib/dhcp/dhclient.leases | grep dhcp-server-identifier

edited Sep 18 '19 at 07:04

Pablo Bianchi

15,657

answered Sep 22 '12 at 05:28

devav2

36,312

3

There is nothing in the /var/lib/dhcp/dhclient.leases, it is empty. – Victor S Sep 22 '12 at 05:36
$ file /var/lib/dhcp/dhclient.leases /var/lib/dhcp/dhclient.leases: empty – Victor S Sep 22 '12 at 05:38
try /var/lib/dhcp/dhclient.eth0.leases – frag Jan 24 '15 at 20:15
3

That a useless use of cat. You probably mean grep domain-name-servers /var/lib/dhcp/dhclient.leases (domain-name, no dhcp-server). – Pablo Bianchi Sep 18 '19 at 07:09

score 9 · Answer 5 · edited Jun 19 '15 at 08:32

9

here it is:

cat /etc/resolv.conf

but do not edit this file

edited Jun 19 '15 at 08:32

muru

197,895
55
485
740

answered Jun 18 '15 at 21:49

Iulian Pojar

107

2

In recent Ubuntu releases (post 2012 I think) it won't be useful, since it will contain nameserver 127.0.1.1, referring to localhost dnsmasq installation. It's better to query NetworkManager as written by @anwar-shah and @marty-fried – gerlos Jan 14 '16 at 10:44
2

As you mention, that file can be edited and thus are not necessarily the addresses assigned by DHCP. Now if you edit it yourself then, obviously, it's going to be different -- but what if you use a company VPN? Or something else influences the file? That's why I think it's not a good answer, even if simple and universal. It's a good first place to look, but not a true answer by itself. – Luc Jul 31 '17 at 22:48
In Ubuntu 22.04 the command grep nameserver /etc/resolv.conf outputs nameserver 127.0.0.53 also if the DNS server are correctly set. – User051209 Jul 21 '23 at 09:37

score 4 · Answer 6 · edited Sep 18 '19 at 23:10

4

As a GUI alternative to @MartyFried's answer, try this.

Click on the Network connectivity icon on the top panel.
Select Wi-Fi Settings
It should show you the DNS server address

edited Sep 18 '19 at 23:10

Pablo Bianchi

15,657

answered Sep 22 '12 at 04:28

Anwar

76,649

4

My Ubuntu has no any GUI desktop. – Victor S Sep 22 '12 at 04:44
@VictorS it shows the same information as the other answer. I checked it – Anwar Sep 22 '12 at 04:46
1

Thanks for your answer, it is convenient for gnome or KDE users. – Victor S Sep 22 '12 at 04:51

score 2 · Answer 7 · edited Nov 12 '19 at 17:13

My actual solution(est 2015, Ubuntu 14.04), is this:

Start the CLI
Type: sudo apt-get install gnome-system-tools
After install succeeded, type at the terminal: network-admin

If you somehow can't do this then try this, though it's not good enough for me, but it got my job done:

type dig google.com
near the end you can see something like this(est. 2015) ;; SERVER: and then an IP address(at least, on my machine) THAT is the actual DNS server resolving the domain for you. That server can change per hostname though.

score 2 · Answer 8 · answered Jun 30 '17 at 14:43

2

In Ubuntu 16.04, the info from dhcp is written in: /var/lib/NetworkManager/dhclient-<interface>.conf

answered Jun 30 '17 at 14:43

Anton Krosnev

123

score 2 · Answer 9 · answered Sep 17 '17 at 21:19

As I mentioned in the comments (which by popular request has become an answer now), one can use nmcli dev show as of Ubuntu 15.04. Add grep to the mix and you're set:

$ nmcli dev show | grep 'DNS'                                                                                                                                                                     
IP4.DNS[1]:                  208.67.222.222
IP4.DNS[2]:                  208.67.220.220

spinpwr · Answer 10 · 2023-10-17T18:22:39.930

The below worked for me on 20.04 LTS and 22.04 LTS:

resolvectl status

It will show the DHCP advertised and current DNS servers for each interface. Any manually configured DNS servers will also show up.
You can see the DNS domain too (which I was looking for when I have found this thread).

Global
       Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (enp0s31f6)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 3 (wlp4s0)
    Current Scopes: DNS
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.0.67
       DNS Servers: 192.168.0.67 192.168.0.66
        DNS Domain: home
Link 4 (docker0)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported

score 0 · Answer 11 · answered Dec 03 '15 at 23:16

If your computer run behind of Router/WiFi of your Internet Provider, you'll get a Private IP Address from DHCP of Router, something like 192.168.0.2 or 192.168.1.100.

To get the Public IP Address of DHCP of DNS from your Internet Provider, you need run the follow command line on terminal:

dig +short myip.opendns.com @resolver1.opendns.com

How to view the DNS address assigned by DHCP?

11 Answers11

Linked