How to Flush DNS Cache on Mac

Your Mac's DNS cache usually operates seamlessly in the background. However, corruption can lead to website loading issues, frequently manifesting as 404 errors. Clearing this cache is a simple solution. The method varies slightly depending on your macOS version. Let's explore the symptoms indicating a necessary cache clear and the steps involved.

What is the DNS Cache?

Understanding the DNS cache requires understanding DNS (Domain Name System). When you access a website, your Mac contacts a DNS server to translate the web address into an IP address – the numerical location of the website's server. This is a DNS lookup.

The DNS cache stores these recent lookups, speeding up future requests and improving website loading times.

Clearing the DNS Cache on Mac

The process differs for newer and older macOS versions:

Newer macOS (Sonoma, Ventura, Monterey, Big Sur, and later):

1. Access Spotlight search (Command Space) and type "Terminal." Open the Terminal app.
2. Execute this command: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
3. Enter your Mac's password and press Enter.

Older macOS (Catalina and earlier):

Use the appropriate command in Terminal:

• macOS El Capitan and later: sudo killall -HUP mDNSResponder
• macOS Yosemite: sudo discoveryutil udnsflushcaches
• macOS Lion, Mountain Lion, Mavericks: sudo killall -HUP mDNSResponder
• macOS Snow Leopard: sudo dscacheutil -flushcache
• macOS Leopard: sudo lookupd -flushcache
• macOS Tiger: lookupd -flushcache

After flushing the cache, check if the website issue is resolved. Persistent problems might require additional troubleshooting, such as removing unnecessary browser extensions or closing resource-intensive applications.

Checking the DNS Cache

Before clearing, you can check the cache's contents:

1. Open the Console app, select your Mac, and search for any:mdnsresponder.
2. In Terminal, run sudo killall -INFO mDNSResponder (enter your password).
3. Review the cached DNS records in Console. Alternatively, use your browser's developer tools (e.g., chrome://net-internals/#dns in Chrome).

When to Flush the DNS Cache

An outdated or corrupted DNS cache can cause connectivity problems, potentially exacerbated by malware. Flushing the cache can resolve issues such as DNS spoofing, 404 errors, website access problems, privacy concerns related to search behavior, and DNS record propagation delays. However, for malware issues, a dedicated malware scan is recommended.

Clearing the Safari DNS Cache

Safari also maintains a DNS cache. While restarting Safari clears it automatically, you can manually clear it:

1. Go to Safari > Preferences > Advanced.
2. Check "Show Develop menu in menu bar."
3. Select Develop > Empty Caches. Restart Safari afterwards.

FAQs

• How often? There's no strict schedule; every six months is a reasonable guideline.
• Is it safe? Yes, it's safe. However, avoid excessively frequent clearing as it negates the performance benefits of caching.

Clearing your Mac's DNS cache is a straightforward troubleshooting step for various internet browsing issues. Remember to consider other potential causes if the problem persists.

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