Ubuntu DNS cache (resolver cache) is a temporary database that contains records of all the recent visits and attempted visits to websites and other internet domains.
DNS cache may become corrupt at some point and may prevent you from resolving websites and other internet domain names if that happens. When that happens, the most common way of resolving the issues is clearing the temporary cache database.
Ubuntu uses systemd-resolved, which is a system service that provides network name resolution to local applications. It implements a caching and validating DNS/DNSSEC stub resolver and responder.
So, if you’re experiencing weird Internet connection issues or browsers not working opening some websites and domains, you may want to clear your DNS cache as well as your web browser stored caches.
This brief tutorial shows students and new users how to clear or flush DNS cache database on Ubuntu systems. When you’re ready to flush Ubuntu DNS cache, follow the steps below:
Before flushing Ubuntu DNS cache, you may want to run a report of the current cache size. To do that, run the commands below.
sudo systemd-resolve --statistics
That should display the DNS statistics showing you all the cache in its database.
DNSSEC supported by current servers: no Transactions Current Transactions: 0 Total Transactions: 30 Cache Current Cache Size: 14 Cache Hits: 16 Cache Misses: 14 DNSSEC Verdicts Secure: 0 Insecure: 0 Bogus: 0 Indeterminate: 0
Flushing Ubuntu DNS Cache
Now that you now the size of the DNS cache, simply run the commands below to clear or flush the cache.
sudo systemd-resolve --flush-caches
If the above commands didn’t flush the DNS cache, you can also use the commands below. Or just all the commands listed here to perform a thorough clean up.
sudo /etc/init.d/dns-clean restart sudo /etc/init.d/networking force-reload
Now go and test to see if your system DNS caches are gone.
Now also clear your browser cache if to make sure you’re able access network domains and other Internet websites.
Hope this post helped your cleaning your Ubuntu desktop DNS cache.
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