Flush the DNS Cache for Lumu

How to Flush the DNS Cache?

DNS caching involves an Operating System (OS) or a browser capturing recently-visited IP addresses and saving them for loading pages more quickly. When DNS settings are updated, clearing the devices’ DNS cache helps you make the devices recognize the updated information faster.

The instructions on this guide provide directions for clearing the DNS cache on computers and servers.

The steps provided here may vary depending on the OS version. If these instructions do not work as expected, consult the relevant documentation for your OS type.

Windows Devices

In order to flush your DNS in a Windows device, open a command prompt window and type:

ipconfig /flushdns

You should receive the following confirmation message:

Successfully flushed the DNS Resolver Cache.

macOS Devices

You must have administrator access in order to run this command.

macOS version 10.5 or 10.6

To clear your DNS cache if you use macOS version 10.5 or 10.6, perform the following steps:
  1. Click on Applications.
  2. Click on Utilities.
  3. Double-click on Terminal.
  4. Run the command:
sudo dscacheutil -flushcache

If the command is executed successfully, the system will not return any output.

macOS version 10.7+

To clear the DNS cache in a macOS version 10.7 and above, follow the steps below:

  1. Click on Applications.
  2. Click on Utilities.
  3. Double-click on Terminal.
  4. Run the command:
sudo killall -HUP mDNSResponder

If the command is executed successfully, the system will not return any output.

Linux

You must have administrator access in order to run these commands.

To flush the DNS cache in most Ubuntu and other Debian-based distributions, open a terminal (gnome-terminal, konsole, xterm, etc.) and run the following command:

sudo systemd-resolve --flush-cache

If the command is executed successfully, the system will not return any output.

For different distributions, check if it is using nscd, dnsmasq, or other packages and search how to clear the DNS cache with those tools. For example, usually Red Hat distributions and Arch Linux use nscd to restart the service to clear out the cache:

sudo systemctl restart nscd

Validate your settings

After flushing the DNS cache, verify that your DNS connections are correctly routed through Lumu. See Validate your DNS Settings for more information.
        • Related Articles

        • How does Lumu compare to a DNS firewall?

          Lumu and DNS firewalls are different technologies, designed with different purposes in mind. For starters, Lumu is a technology that was built from the ground up with a single objective: help to measure and understand your unique compromise level in ...
        • How can Lumu and DNS Firewalls work together?

          If your company already has a DNS firewall like OpenDNS (currently, Cisco Umbrella), Infoblox, or the like, Lumu Insights seamlessly integrates with your DNS firewall to continue to benefit from blocking malicious DNS requests, while layering ...
        • Can Lumu replace the DNS Firewall?

          DNS firewalls and Lumu are solutions used to address different challenges. Lumu can add incredible value to the security strategy of your organization whether you have a DNS firewall or not. Organizations that have not invested in a DNS firewall find ...
        • How is the network metadata collected?

          On Lumu Free you may use Lumu’s public DNS as forwarders on your internal DNS Servers. On Lumu Insights and Lumu Defender, we rely on virtual appliances and cloud collectors to cover your hybrid environments. Consult our deployment documentation for ...
        • Circumvention and Firewall Rules

          Savvy users may try to modify their DNS settings to circumvent the environment’s default DNS settings. Most routers and firewalls will allow you to force all DNS traffic over port 53 on the router, thus requiring everyone on the network to use the ...