How to Flush DNS Cache on Mac, Windows & Linux
ChatGPT
Claude
Gemini
Perplexity
GrokIn brief
Clear your DNS cache in one command (macOS, every Windows version, and Linux distros) plus how to flush browser DNS and confirm it worked.
The Domain Name System (DNS) translates human-readable domain names into the IP addresses computers actually connect to. To speed things up, your operating system caches those lookups locally, but a stale cache can serve outdated records, which is exactly the problem when you've just changed an MX, TXT, or CNAME record and the old value keeps resolving. Flushing the DNS cache forces your system to fetch fresh data. The command differs by operating system: ipconfig /flushdns on Windows, sudo killall -HUP mDNSResponder on macOS, and sudo resolvectl flush-caches on most Linux distributions running systemd-resolved.
What the flush DNS command does
The flush command tells your operating system to discard its cached DNS entries, so the next lookup for any domain retrieves current data from your DNS servers. It's the fastest fix when a record change hasn't taken effect locally, when a site resolves to the wrong address, or when you're troubleshooting connectivity that points at DNS.
Each OS has its own flush command; Linux commands vary by distribution.
Each operating system has its own command, so let's walk through Windows, macOS, and Linux in turn.
Flushing DNS cache on Windows
- Open Command Prompt as an administrator. Press the Windows key, type "Command Prompt," right-click it, and choose "Run as administrator."
- Run the flush command. Type
ipconfig /flushdnsand press Enter. Windows clears its resolver cache. - Confirm it worked. You should see the message "Successfully flushed the DNS Resolver Cache."
ipconfig /displaydns.
Flushing DNS cache on macOS
- Open Terminal. Go to Applications → Utilities and launch Terminal.
- Run the flush command. Type
sudo killall -HUP mDNSResponderand press Enter. This signalsmDNSResponder, the process responsible for DNS caching, to clear its cache. - Enter your password. You'll be prompted for your administrator password; it won't display as you type. Press Enter.
Flushing DNS cache on Linux
Linux distributions handle DNS caching differently, so the command depends on which resolver your system runs.
- Open a terminal. Use a shortcut like Ctrl+Alt+T or search for "Terminal" in your application launcher.
- Run the command for your resolver:
sudo systemd-resolve --flush-caches (or sudo resolvectl flush-caches on newer releases).
- NetworkManager: sudo systemctl restart NetworkManager.
- dnsmasq: sudo systemctl restart dnsmasq.
If you're unsure which resolver you use, systemd-resolved is the default on most modern distributions. Consult your distribution's documentation for anything unusual.
Flushing your browser's DNS cache
Browsers keep their own DNS cache that survives an OS-level flush. In Chrome, visit chrome://net-internals/#dns and click "Clear host cache"; in Firefox, DNS is cached briefly and clears on restart. If a site still resolves incorrectly after an OS flush, clear the browser cache too.
When flushing isn't enough
While flushing the cache resolves many issues, some DNS problems need a closer look.
Work through these when a cache flush alone doesn't fix DNS resolution.
- DNS errors and misconfigurations: Double-check your records with the DNS lookup tool to confirm the published values are what you intended.
- DNS cache poisoning and spoofing: Keep your DNS software current and use protective measures against cache poisoning.
- Network connectivity and server availability: Confirm your connection is stable and your DNS servers are reachable.
- Firewall and security settings: Make sure a firewall or security tool isn't blocking DNS requests on port 53.
Common issues when flushing DNS
The flush command runs but the old record still resolves.
The record's TTL controls how long resolvers upstream of you keep the old value; your local flush can't clear their caches. It can also be your browser's separate cache. Wait for the TTL to expire, flush the browser cache, and confirm with the DNS lookup tool rather than the browser.
"The requested operation requires elevation" on Windows.
ipconfig /flushdns needs administrator rights. Close the window and reopen Command Prompt with "Run as administrator" before running the command again.
macOS shows no confirmation message.
That's expected, killall -HUP mDNSResponder prints nothing on success. If you got no error, the flush worked. Test by resolving a domain that recently changed.
The Linux command isn't found or has no effect.
You're likely targeting the wrong resolver. Check whether systemd-resolved, NetworkManager, or dnsmasq is running with systemctl status, then use the matching command from the list above.
Simplify DNS and email troubleshooting with Palisade
Getting DNS right and keeping it right is the foundation of reliable, secure email. Palisade gives you visibility into your DNS and email-authentication setup, flags misconfigured records before they cause delivery problems, and shows you exactly what to fix. Start with the free Email Security Score to see where your domain stands.
Related reading
Questions readers ask
Frequently asked questions
Does flushing DNS delete anything important?
No. It only clears cached lookups, which your system rebuilds automatically on the next request. Nothing about your configuration, bookmarks, or files is affected.
How often should I flush my DNS cache?
Only when you need to, typically right after changing a DNS record, or when troubleshooting a site that resolves to the wrong address. There's no benefit to flushing on a schedule.
Why does a record still resolve to the old value after I flush?
Because caching happens at multiple layers. Your OS cache is cleared, but resolvers between you and the authoritative server still hold the old record until its TTL expires. Lowering the TTL before a planned change reduces this delay.
Will flushing DNS fix email delivery problems?
Only indirectly. If you just published a new SPF, DKIM, or DMARC record and are testing locally, a flush lets you see the current value sooner. Verify authentication records with the Email Security Score rather than relying on cached lookups.
Written by
Dominic LandryDeliverability & DNS
Dominic Landry works on email deliverability and DNS configuration at Palisade, from SPF and DKIM records through to DMARC enforcement.
More from Dominic →
