Dashboard Policies and DNS Caching

The App Dashboard

When making any changes in the DNSFilter Dashboard, all changes are applied to our system instantaneously. There is no delay in DNSFilter respecting and enforcing your changes.

DNS record information is usually cached (stored on your local computer or network) for a specific amount of time; anywhere from 5 minutes to 8 hours is normal.

This article explains and sets expectations regarding basic DNS caching behavior when using DNSFilter, as well as provides basic instructions for checking and clearing cache.

Confident you've already done all the cache clearing humanly possible?  See here. If not, plrease read on.


Policy Changes

Whitelisting and Allowing
When adding domains to a policy's whitelist, or deselecting categories from being blocked, you can expect to see the changes reflected in your network/computers within 30 seconds.  DNSFilter block pages have a 30-second cache time (TTL), so there should normally be no need to clear the cache on your computer or browser. This is not gauranteed, as Chrome and some networking devices force a minimum cache time (TTL) of 60 seconds or more.

Blacklisting, Blocking, and Changing Policies
When adding domains to a policy's blacklist, selecting additional categories to be blocked, or assigning a different policy to a network, domains may have been visited recently on computers in your network, and therefor the cache time (TTL) as set by the domain's DNS administrators, could take minutes or hours to expire.

If you've recently made a change to your policy settings, and want to see the changes immediately and without waiting for the cache (TTL) to expire, read on.


Clearing Cache

Before contacting support, and/or considering the possibility of other issues with content filtering, we ask you to clear your cache on both your web browser (if using the browser to test) and your operating system. 

Mac OSX 10.9 and Later:
1.) Launch the Terminal application
2.) Run the following command and hit enter: 
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder


Mac OSX 10.8 and Earlier:
1.) Launch Terminal (under Applications/Utilities)
2.) Run the following command and hit enter:
sudo killall -HUP mDNSResponder


Windows 7 and Earlier:
1.) Open the Start Menu
2.) Click “All Programs”
3.) Choose “Accessories” and right-click on the program named “Command Prompt”
4.) If prompted, allow to run as Administrator
5.) Run the following command and hit enter: 
ipconfig /flushdns

Windows 8 and Later:
1.) Click the Windows Icon on the lower left hand corner
2.) Search for “Command Prompt” and launch the program.
3.) If prompted, allow to run as Administrator
4.) Run the following command and hit enter:
ipconfig /flushdns

Linux (Ubuntu)
1. Open a terminal window. 
2. Run the following command and hit enter: 
sudo service network-manager restart

Firefox:
1.) Type about:config in Firefox’s address bar and acknowledge the warning that appears
2.) Find an entry called  network.dnsCacheExpiration and set it’s value to 0
2b.) If there’s no such entry, create a new integer item with the name above and a value of 0
3.) Now go back and change the value to 3600

Safari (Windows and Mac):
Resetting the DNS Cache in Windows automatically flushes the DNS cache on Safari. Nothing to do here!

Google Chrome (Windows and Mac):
1.) In a new tab, type the following into the address bar and hit enter:
chrome://net-internals/#dns
2.) Click the button labeled clear host cach


Troubleshooting

If you're still not seeing content filtered properly properly, we'd like to take this opportunity to mention that  DNSFilter requires only using our DNS servers in your DNS configuration

Still having trouble? Reach out to us.

Still need help? Contact Us Contact Us