How can I check which DNS server am I using (in Linux)? I am using network manager and a wired connection to my university's LAN. (I am trying to find out why my domain doesn't get resolved)
You should be able to get some reasonable information in:
$ cat /etc/resolv.conf
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25However, please be aware that (on modern Linuxen) the contents of
/etc/nsswitch.confdictate what name services are used (DNS, LDAP, etc) and in what order. Sayfgrep hosts: /etc/nsswitch.conf. If it only references DNS,/etc/resolv.confis the right place to look for your nameservers. But chances are you're also using mDNS (aka ZeroConf, aka Avahi, aka Bonjour, etc), etc. In that case, things depend on what you're using. – Alexios Jan 12 '12 at 13:35 -
18This file typically points at 127.0.1.1 on Ubuntu - it's the local DNS cache server, not the actual upstream. – Barry Kelly Mar 8 '16 at 10:24
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1And if you have several upstream server configured ? How to know which one is currently used ? – Sylvain Leroux Nov 24 '16 at 23:31
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1I would suggest to mention that file is a link and dynamically generated for systems using resovconf (like Ubuntu). I've seen this answer millions of times and until today is that I think it is correct, because I understand now that it is actually a dynamically generated file. – jgomo3 Dec 26 '17 at 18:00
Here's how I do it:
nmcli dev show | grep DNS
This worked previous to the way above:
nm-tool | grep DNS
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9This one is usefull if you are using VPN and NetworkManager. Your
/etc/resolv.confwill point to your machine, withdnsmasqresolving names as configured by NetworkManager. – Grzegorz Żur May 30 '13 at 11:32 -
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2nm-tool is not available in newer linuxes. for example it is not in the 'network-manager' package of debian 8. – don bright Oct 31 '15 at 15:06
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nm-tool | grep DNS No command 'nm-tool' found, did you mean: Command 'dm-tool' from package 'lightdm' (main) nm-tool: command not found– chovy Aug 31 '16 at 7:22 -
I think you can also query DNS and it will show you what server returned the result. Try this:
dig yourserver.somedomain.xyz
And the response should tell you what server(s) returned the result.
You can also tell dig to query a specific DNS server by using dig @server_ip
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2If you use any DNS masking/caching service that is run on your local machine, it will hide the real DNS servers. – karatedog Sep 7 '15 at 9:12
Just do an, nslookup. Part of its results include the server that it's using.
In the example below, it shows that the DNS server used is at 8.8.8.8.
$ nslookup google.com
Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
Name: google.com
Address: 172.217.22.174
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2On a recent Ubuntu, this again points to the local cache server 127.0.0.1 as already hinted at in this comment – FriendFX Dec 1 '17 at 1:50
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In CentOS 7 it quits with error, but it is a vm so I did
nslookup google.comin the Windows host and I found the nameserver. Add it in/etc/resolv.conflike:nameserver xx.xx.xx.xxand restart servicenetwork, and all is fine. Praise you. – WesternGun May 3 at 15:22
With the new network-manager command nmcli, do this:
nmcli --fields ipv4.dns,ipv6.dns con show <connection_name>
On newer versions of network-manager (such as in Ubuntu 16.04), the field names are slightly different:
nmcli --fields ip4.dns,ip6.dns con show <connection_name>
If you don't know the connection name, use:
nmcli -t --fields NAME con show --active
For example:
$ nmcli --fields ip4.dns,ip6.dns con show 'Wired connection 1'
IP4.DNS[1]: 172.21.0.13
IP4.DNS[2]: 172.21.0.4
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It works fine for me with network-manager 1.0.4 on Ubuntu 15.10. Maybe you have an older version? – Sameer Mar 17 '16 at 5:40
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The tabular format is pretty bad. I hope to get a column like format similar to Powershell. – CMCDragonkai Mar 14 '17 at 6:42
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1Returns
Error: invalid field 'ip4.dns'; allowed fields: NAME,UUID,TYPE,TIMESTAMP,TIMESTAMP-REAL,AUTOCONNECT,AUTOCONNECT-PRIORITY,READONLY,DBUS-PATH,ACTIVE,DEVICE,STATE,ACTIVE-PATH.– FriendFX Dec 1 '17 at 1:53
If you are using network manager probably you get all network parameters from your dhcp server at your university.
If you don't want use your shell to check your dns settings (as described by hesse and Alexios), you can see them from the panel "Network information".
You can reach this panel by pressing right mouse button on network manager icon and selecting "Connection Information" from the menu.
to get the first DNS SERVER (IP only) :
cat /etc/resolv.conf |grep -i '^nameserver'|head -n1|cut -d ' ' -f2
catwill output DNS configgrepfilters only nameserverheadwill keep only the first row/instancecuttake the ip part of the row (second column with ' ' as separator)
To put DNS ip in an environment variable, you could use as follow:
export THEDNSSERVER=$(cat /etc/resolv.conf |grep -i '^nameserver'|head -n1|cut -d ' ' -f2)
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To lighten the pipeline even more, capture groups with Perl regexp is very neat, and grep takes a file argument:
grep -Pom 1 '^nameserver \K\S+' /etc/resolv.conf. Just wrote up Capture groups with grep perl regular expression – sshow Jul 28 '17 at 9:04
On systems running systemd use:
systemd-resolve --status
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Says
Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found.– xji Apr 12 at 11:19 -
1This is the new default way to do it in Ubuntu 18.04 Bionic Beaver - get used to it, everybody! – AveryFreeman Apr 24 at 20:32
The command
nmcli dev list iface <interfacename> | grep IP4
Replace "interfacename" with yours.
examlpe
nmcli dev list iface eth0 | grep IP4
This will list all DNS servers(If you use more than one).
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1On debian i get an error--- $ nmcli dev list iface eth0 Error: 'dev' command 'list' is not valid. – don bright Oct 31 '15 at 15:00
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I have Fedora 25 and also had similar slow response on command line to sudo commands.
nmcli dev show | grep DNS
showed that only one of my 3 adapters (two active) had DNS entries. By adding DNS entries to the one active card that didn't have an entry - presto! All is good and response time is immediate.
In CentOS, you can use:
/usr/sbin/named -v
