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FAQ 12: How to flush DNS cache

Category: Troubleshooting | Updated: 12/05/2016 11:34 AM


To flush your DNS cache follow all the steps below...

A) close all Internet browsers (modern browsers maintain their own DNS cache)
   Ensure the browser is actually closed, just because you can't see the window doesn't mean it always closed,
   check task manager for running processes such as: iexplore.exe, firefox.exe, chrome.exe
   If you are using some other software that does a DNS lookup (such as a mail client [Outlook/Thunderbird], IM, VPN, remote desktop, game, etc.) close it as well.

B) flush the local machine DNS cache (restarting the computer will also accomplish this)
   Windows: Start > Run > Type: cmd > Enter > Type: ipconfig /flushdns > Enter(b)
   Mac OSX 10.4 (Tiger): Terminal(a) > Type: lookupd -flushcache > Enter(b)
   Mac OSX 10.5 & 10.6 (Leopard): Terminal(a) > Type: sudo dscacheutil -flushcache > Enter(b)
   Mac OSX 10.7 & 10.8 (Lion): Terminal(a) > Type: sudo killall -HUP mDNSResponder > Enter(b)
   Mac OSX 10.9 (Mavericks): Terminal(a) > Type: dscacheutil -flushcache;sudo killall -HUP mDNSResponder > Enter(b)
   Ubuntu/Lubuntu: Terminal window > Type: sudo service network-manager restart > Enter(b)
   Most other Linux installs: Terminal window > Type: sudo /etc/init.d/nscd restart or: sudo /etc/init.d/networking restart > Enter(b)

C) if you have any internal DNS servers, such as your Active Directory (AD) Domain Controller (DC), flush the cache here also
   Windows: Control Panel > Administrative Tools > DNS > right-click on the server name, pick Clear Cache
                 or from the command-line by running: c:\windows\system32\dnscmd.exe . /clearcache

(a) found in the dock, or in Finder > Applications > Utilities
(b) after pressing Enter the command runs and the local DNS cache is cleared

Note: Windows may require elevated privileges
Start > All Programs > Accessories > right-click "Command Prompt" > select "Run as Administrator" > then type the command

Note: It is not mandatory to manually clear the DNS cache, a change to your DNS Redirector allowed or blocked configuration will eventually take effect on all network clients, depending on the TTL of the DNS record it could be within minutes or several hours.



Legacy information provided for reference only: it is not suggested that you disable DNS cache...

While disabling client DNS cache creates more DNS traffic across the LAN, it would ensure that all records get the most accurate/current resolve. You should take care in forcing this change only on computers under your direct control (within your company or organization).

Windows 2000: kb245437
Windows XP/2003: kb318803

For more information on how DNS works read here.

Also see, How Internet Explorer uses the cache for DNS host entries: kb263558



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