What dns server is my linux server using

What DNS servers am I using?

The Linux kernel itself is not aware about DNS services. To answer it’s better to know your userland. What distribution are you using? Ubuntu? Debian GNU/Linux? Centos?

14 Answers 14

You should be able to get some reasonable information in:

However, please be aware that (on modern Linuxen) the contents of /etc/nsswitch.conf dictate what name services are used (DNS, LDAP, etc) and in what order. Say fgrep hosts: /etc/nsswitch.conf . If it only references DNS, /etc/resolv.conf is 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.

This file typically points at 127.0.1.1 on Ubuntu — it’s the local DNS cache server, not the actual upstream.

See the answers by @G32RW or @Lonniebiz for a more robust approach under various circumstances, e.g. when you get an answer like 127.0.0.53

This solution is no more up to date. I find the systemd-resolve —status suggested by @G32RW most up-to-date solution for this problem.

( nmcli dev list || nmcli dev show ) 2>/dev/null | grep DNS 

On Debian, you need to have the network-manager package installed.

This one is usefull if you are using VPN and NetworkManager. Your /etc/resolv.conf will point to your machine, with dnsmasq resolving names as configured by NetworkManager.

nm-tool is not available in newer linuxes. for example it is not in the ‘network-manager’ package of debian 8.

This did not work for me on an Ubuntu VM. nmcli dev show did not have the DNS info. However, systemd-resolve —status did have the real DNS server. unix.stackexchange.com/a/434756

On systems running systemd use:

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. The output you’re interested in will look something like this:

;; Query time: 91 msec ;; SERVER: 172.xxx.xxx.xxx#53(172.xxx.xxx.xxx) ;; WHEN: Tue Apr 02 09:03:41 EDT 2019 ;; MSG SIZE rcvd: 207 

You can also tell dig to query a specific DNS server by using dig @server_ip

If you use any DNS masking/caching service that is run on your local machine, it will hide the real DNS servers.

This only tells you which server was used for that query. It doesn’t tell you all the DNS servers that your host might use.

Beware that this obviously fails if the DNS server is not available. That’s not a common thing, but I’ve managed to get a bad result or timeout when looking for a DNS server running on IPv6 (using dig -6 ).

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 

On a recent Ubuntu, this again points to the local cache server 127.0.0.1 as already hinted at in this comment

In CentOS 7 it quits with error, but it is a vm so I did nslookup google.com in the Windows host and I found the nameserver. Add it in /etc/resolv.conf like: nameserver xx.xx.xx.xx and restart service network , and all is fine. Praise you.

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, on old versions of nmcli :

$ 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 

Returns Error: invalid field ‘ip4.dns’; allowed fields: NAME,UUID,TYPE,TIMESTAMP,TIMESTAMP-REAL,AUTOCONNECT,AUTOCONNECT-PRIORITY,READONLY,DBUS-PATH,ACTIVE,DEVICE,STATE,ACTIVE-PATH.

to get the first DNS SERVER (IP only) :

cat /etc/resolv.conf|grep -im 1 '^nameserver' |cut -d ' ' -f2 

• cat will output DNS config
• grep filters only nameserver
• -i grep ignore case
• -m 1 grep stop after first match
• cut take 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 -im 1 '^nameserver' |cut -d ' ' -f2) 

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

There’s both IPv4 and IPv6 DNS servers. Also, secondary servers exist for a reason. Which one this command returns? Is it advised to take the first one, and just ignore the others?

Using resolvectl

$ resolvectl status | grep -1 'DNS Server' DNSSEC supported: no Current DNS Server: 1.1.1.1 DNS Servers: 1.1.1.1 1.0.0.1 

grep option: -C NUM , -NUM , —context=NUM Print NUM lines of output context.

For compatibility, systemd-resolve is a symbolic link to resolvectl on many distros as for Ubuntu 18.10:

$ type -a systemd-resolve systemd-resolve is /usr/bin/systemd-resolve $ ll /usr/bin/systemd-resolve lrwxrwxrwx 1 root root 10 nov. 15 21:42 /usr/bin/systemd-resolve -> resolvectl $ type -a resolvectl resolvectl is /usr/bin/resolvectl $ file /usr/bin/resolvectl /usr/bin/resolvectl: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=09e488e849e3b988dd2ac93b024bbba18bb71814, stripped 

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Linux what dns server am i using

You can just use grep command to get DHCP server address, enter: OR Solution 2: I recently had this problem where my was misconfigured as was not setting DNS servers. Dnsmasq forwards DNS queries to the DNS servers whose addresses have been provided by the DHCP server.

What is my DNS server?

As en expansion of happyskeptic’s answer, you don’t need to specify an interface. This does it for me:

> nmcli dev show | grep DNS IP4.DNS[1]: 172.22.216.251 IP6.DNS[1]: 2a01:4f0:400c:1::1 

For Ubuntu 14.04 and older use nmcli dev list | grep DNS

> nmcli dev list | grep DNS IP4.DNS[1]: 172.22.216.251 IP6.DNS[1]: 2a01:4f0:400c:1::1 

You are using dnsmasq , a lightweight forwarding DNS server that runs locally under the control of NetworkManager. Dnsmasq forwards DNS queries to the DNS servers whose addresses have been provided by the DHCP server. It is also possible to set these DNS server addresses statically using the Connection Editor.

The dnsmasq executable is provided by the dnsmasq-base package on which the network-manager package depends. There is also a package called simply «dnsmasq» which also depends on dnsmasq-base, but this «dnsmasq» package should only be installed if you want to run dnsmasq independently of NetworkManager in order to take advantage of features other than mere DNS forwarding.

I’ve found that on Kubuntu 14.04 the NetworkManager applet (or Plasma thing, whatever it’s called) in KDE doesn’t show the DNS server info under the connection details.

In this case the way to find it is to run the following at the command line and look for the lines ‘IP4.DNS’:

nmcli dev list iface wlan0 

(replace wlan0 with the interface you use to connect to the Net)

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Find out the DNS server for a DHCP connection in Linux

Usually dhclient.leases file is located at /var/lib/dhcp3/dhclient.leases , type the following command:

You can just use grep command to get DHCP server address, enter:

grep dhcp-server-identifier /var/lib/dhcp3/dhclient.leases

I recently had this problem where my dhcpcd was misconfigured as was not setting DNS servers. I found out that I can query which nameservers are available by DHCP with the following command:

sudo dhcpcd -o domain_name_servers -T 

The command will output a bunch of network connection information. Look for the line beginning with new_domain_name_servers .

From here I was able to manually set the nameservers.

One more solution to query the DHCP server:

sudo nmap --script broadcast-dhcp-discover 

The output tells you the name server offered by the DHCP server:

Starting Nmap 7.60 ( https://nmap.org ) at 2019-12-12 23:50 UTC Pre-scan script results: | broadcast-dhcp-discover: | Response 1 of 1: | IP Offered: 144.123.211.44 | DHCP Message Type: DHCPOFFER | Server Identifier: 144.123.99.200 | IP Address Lease Time: 5m00s | Subnet Mask: 255.255.0.0 | Router: 144.123.99.200 | Domain Name Server: 144.123.99.200 |_ Domain Name: localdomain 

Linux — DNS Server — how to differentiate clients?, I am running my own DNS server on a remote machine using Bind9. This server is currently only used by machines that are connected to the same router. The problem that I am having is that as the DNS server is used on a single network, all of the client machines that connect to it have the same external IP.

Find out what DNS servers are being queried?

Hello I think this may be half of your question,

plutes@plutes-Lenovo-G50-30:~$ dig https://askubuntu.com ; > DiG 9.11.3-1ubuntu1.1-Ubuntu > https://askubuntu.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER 

arif@arif:~$ dig google.com ; > DiG 9.10.3-P4-Ubuntu > google.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER 

arif@arif:~$ dig @216.146.35.35 linux.org ; > DiG 9.10.3-P4-Ubuntu > @216.146.35.35 linux.org ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER 

arif@arif:~$ nslookup google.com Server: 192.168.97.54 Address: 192.168.97.54#53 Non-authoritative answer: Name: google.com Address: 74.125.200.102 

arif@arif:~$ nslookup linux.org 216.146.35.35 Server: 216.146.35.35 Address: 216.146.35.35#53 Non-authoritative answer: Name: linux.org Address: 104.28.16.26