Nameserver resolvconf Ubuntu


Ubuntu uses the nameserver resolvconf program to configure local DNS resolution. The resolvconf package includes a simple database and a runtime for dynamically modifying nameserver information.

Nameserver resolvconf Ubuntu

Ubuntu nameserver resolvconf NetworkManager

Typically, the program resolvconf runs through a network interface to push routines such as ifup, ifdown, NetworkManager, dhclient, and pppd, or local nameservers such as dnsmasq to update the DNS information.

If static IP addresses and DNS records are used on a host, the resolvconf package should be deactivated under Ubuntu, so that the DNS configuration from the dnsmasq daemon is not automatically made, the configuration that has been edited in /etc/resolv.conf and /etc/network/interfaces will otherwise be overwritten by the resolvconf program.

Disable nameserver resolvconf

$ resolvconf --disable-updates

Disable Ubuntu resolvconf from boot level and quit the program.

$ systemctl disable systemd-resolved.service
$ service systemd-resolved stop

Customize the Network Manager with default DNS.

$ vi /etc/NetworkManager/NetworkManager.conf

Remove the symlink resolv.conf under /etc.

$ rm /etc/resolv.conf

Edit resolv.conf

and create a new resolv.conf file with the nameservers. in this example, it’s Google Public DNS.

  On a local network or ADS the internal nameservers should be used.

$ vi /etc/resolv.conf


Delete the resolv.conf file of the systemd configuration program.

$ rm /etc/systemd/resolved.conf

change the configuration.

$ service network-manager restart

nameservers can also be defined in the interface configuration.

$ vi /etc/network/interfaces

auto lo
iface lo inet loopback

auto ens160
iface ens160 inet static
  dns-search my.local

The interface name (ens160) may differ and must correspond to that of the respective host.

  The /etc/resolv.conf file should not be missing.

Now enable the new network settings it will be read into memory.

$ /etc/init.d/networking restart

Troubleshooting using DNS

Many network issues are due to incorrect DNS or incorrect configuration of resolver. In a home network there is often no internal DNS, whereby the router or the firewall can be used as a nameserver, such as the Linksys or Netgear router. Basically, it should be ensured that the firewall used has a DNS cache, with semi-professional firewalls such as the FortiGate that not every model provide such a cache. For open source-based firewalls most provide a cache through DNS forwarder or dnsmasq.

After open up a command prompt will changes to the nameservers in Windows, the DNS cache should be reset.

C:\> ipconfig /flushdns

For Linux, the DNS cache can be reset out from terminal, with one of the following commands, depending on which service is installed.

$ sudo /etc/init.d/nscd restart
$ service nscd restart
$ service nscd reload
$ sudo /etc/init.d/dnsmasq restart
$ service dnsmasq restart
$ rndc reload

In the Mac OS X terminal as root.

$ lookupd -flushcache

If there is no internal DNS in the local network, the name servers of the Internet provider can be used, or may the Cloudflare public DNS.

Example of a nameserver querying its provider on Windows.

C:\> nslookup -type=ns

Non-authoritative response: nameserver = nameserver = internet address =

Example nameserver lookup query on Linux.

$ host -t ns name server name server

host & host has address has address has IPv6 address 2a01:2a8:2001:252::11

A ping -n1 resolves addresses to host names with parametersa and4 for IPv4 address.

C:\> ping -4 -n 1 -a

Ping runs for with []32 bytes of data:
Response from Bytes=32 Time=32ms TTL=50

Ping statistics for
    Packages: Sent = 1, Receive = 1, Lost = 0
    (0% loss),
Approx. times in millisec.:
    Minimum = 32ms, Maximum = 32ms, Mean = 32ms

Show the current DNS nameservers available use systemd resolver.

$ systemd-resolve --status

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