DNS Cache (or DNS resolver cache) is a small temporary database maintained by the operating system. It stores the information about all visited websites and other internet domain. In other words, the DNS cache stores recent DNS lookups.

Firefox clear DNS Cache

change config network.dnsCacheExpiration

  • about:config, click "I accept the risk!"

  • search for “network.dnsCacheExpiration” -> change it from 60 to 0

about:networking#dns

  • about:networking#dns

  • about:config - network.trr.mode 0 -> 5

Linux DNS caching services

  • Systemd-resolve

  • Nscd (name service cache daemon)

  • Named/BIND (Berkeley Internet Name Domain)

  • Dnsmasq

Check service status

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systemctl status systemd-resolve
systemctl status nscd
systemctl status named # for Bind
systemctl status dnsmasq

systemd-resolve

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sudo systemctl restart systemd-resolved
systemd-resolve --statistics
systemd-resolve --flush-caches

Nscd

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sudo systemctl restart nscd

Bind/Named

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sudo systemctl restart named
rndc reload
rndc exec
rndc flushname ostechnix.com
rndc flush lan
rndc flush wan

Dnsmasq

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sudo systemctl restart dnsmasq

Ref