How To Flush DNS – Everything You Need To Know

Caches are incredibly useful ways of optimising the experience of browsing websites, as they store often-accessed data in a memory location that can be accessed more quickly than always returning the access request to the server.

That means faster load times, as a device can store a local copy, so the site data requested by the browser can be retrieved and displayed more quickly on subsequent visits. 

However, caching isn’t without its downsides, as information can get outdated and cause connection issues, come under threat from attack, or make it easier for hackers to track online behaviours. 

Your Domain Name System (DNS) translates the domain name of a website into an IP address, so the browser knows where to direct you. 

You can read our full explainer on DNS here. 

A DNS cache, therefore, is a temporary store within your operating system of previous DNS lookups. It contains several components (which you will be able to find within the DNS Zone editor).

These are:

 

• Record Name: a DNS entry’s domain name 
• Record Type: a DNS entry’s record type, which will be either A or AAAA 
• Resource data: a DNS entry’s description, containing the address and hostname
• Resource data length: refers to the resource data’s value
• Class: the protocol group of your resource record 
• Time to live (TTL): the length of time (in seconds) that the record is valid for 

Most of the time, you don’t have to worry about flushing your DNS. That’s because your DNS cache will automatically renew itself based on the TTL, refreshing the data it has stored in an effort to ensure that its cached results aren’t out of date. Plus, if you reboot the DNS server at any time, your DNS cache will automatically clear. 

Although a DNS cache reduces load times for frequently visited sites, flushing the DNS won’t have a hugely noticeable impact on your overall internet browsing speed. So, should you find yourself needing to flush DNS, you should do so in the confidence that it won’t adversely affect your browsing experience. 

As some issues can occur before the TTL is up, there are a few situations in which learning how to flush DNS can be beneficial. Manually flushing the DNS cache will force the cache to clear, so you’ll be able to access just the live sites, rather than your stored version. 

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While there’s not usually a need to worry about making the change yourself, there are a few situations that might prompt you to flush the DNS manually. 

If you’re experiencing one of the following, you might want to consider a DNS cache flush:

Different operating systems have different ways of flushing the DNS. In these step-by-step guides, we’ll explain how to flush DNS using common operating systems – and a couple of browsers, too (which you should do in conjunction if you regularly use them).

How to flush DNS in Microsoft Windows XP, 7, Vista, 8, 8.1 or 10 

The process for flushing DNS in Windows is largely similar across most versions. To begin, you’ll have to use the ‘run as administrator’ option during the command prompt in order to access the system security permissions you’ll need. 

1. Use the Windows + R shortcut to open the ‘Run’ window 
2. Type ‘cmd’ to open Windows Command Prompt
3. Type the following command, and hit ‘Enter’: ipconfig /flushdns

How to flush DNS in macOS X

The command prompt you’ll need to run differs depending on which software version your Mac is running. (You can find out which you need by clicking the Apple icon in the top left corner, followed by ‘About this Mac’.) 

1. Open ‘Finder’, and click ‘Applications’ 
2. Open ‘Terminal’ within the ‘Utilities’ folder 
3. Type in the following command (depending on which macOS you’re running): 
   1. 0.7-10.9, 10.11-10.14 (Lion, Mountain Lion, Mavericks, El Capitan, Sierra, High Sierra, Mojave): sudo killall -HUP mDNSResponder
   2. 11 (Big Sur) or 12 (Monterey): sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
   3. 10.10 (Yosemite): sudo discoveryutil mdnsflushcache
   4. 10.5-10.6 (Leopard, Snow Leopard): sudo dscacheutil -flushcache
   5. 10.4 (Tiger): lookupd -flushcache
4. Enter your password, and hit ‘Enter’ 

How to flush DNS in Linux 

Linux is a popular operating system – and the one which powers Android devices. It doesn’t cache DNS records by default, but you can choose to manually install a DNS service – which you’ll then have to access via the ‘Terminal’ application (Ctrl + Alt + T) in order to flush. 

1. 1. Once you’ve opened the ‘Terminal’ window, type in one of the following commands (depending on which service your Linux system is using): 
      1. NCSD: sudo /etc/init.d/nscd restart
      2. Dnsmasq: sudo /etc/init.d/dnsmasq restart
      3. BIND: You may have to try multiple commands:

• sudo /etc/init.d/named restart

• sudo rndc restart

• sudo rndc exec

1. 1. Systemd: systemd-resolve –flush-caches
2. You may be prompted to enter your password before the reset will occur

How to flush DNS in Google Chrome 

Although Google Chrome is not itself an operating system, it does keep its own DNS cache, which means that if you regularly use it – or have it as your default browser – it’s worth flushing its separate DNS cache too. 

1. Navigate to this address via your browser: chrome://net-internals/#dns
2. Click the ‘Clear host cache’ button 

How to flush DNS in Firefox 

If Firefox is your default browser, learning how to flush DNS is even easier, as the cache is not kept on the disk as therefore it’s as simple as just restarting your browser. However, if you’d prefer not to restart your browser, you can follow similar steps to the Google Chrome process: 

1. Navigate to this address via your browser: about:networking#dns
2. Click the ‘Clear DNS Cache’ button

How to flush DNS in Microsoft Edge 

There are two different ways to flush the DNS if Microsoft Edge is your default browser – depending on whether you use Edge Chromium or the Edge legacy browser.