How to Flush Your Operating System’s DNS Cache

When you edit domain records or change IP addresses, you may find that you can no longer access a site on the server. Instead of loading the site’s pages, you get a 404 “Not Found” error. That may be because the DNS record changes haven’t propagated, but it can also be caused by stale entries in your operating system’s DNS cache. 

DNS records change infrequently, and it takes time to make a request to domain name servers. It’s often quicker to make a DNS request and cache the results for a while. That way, the domain’s IP address can be read from the cache, which is much faster than getting it from a DNS server across the internet.

However, if you make a change and the DNS record no longer matches your cache, you won’t be able to load the site. On most operating systems, it’s straightforward to clear the cache, forcing the OS to get fresh data.

Microsoft^® Windows 10

Launch the command prompt by entering “cmd” in the start menu search box, right-clicking on Command Prompt, and selecting Run as Administrator. Enter the following command:

ipconfig /flushdns 

All being well, you’ll see the message: “Windows IP configuration successfully flushed the DNS Resolver Cache.”

macOS^®

On OS X Yosemite and later, open your preferred terminal emulator or type “terminal” into Spotlight. Enter this command followed by the administrator account’s password.

sudo killall -HUP mDNSResponder

On older versions of macOS, use the following command instead:

sudo discoveryutil mdnsflushcache

CentOS

Run the following in a terminal window:

systemctl restart dnsmasq.service