Browser(application) level:

For Google Chrome/Chromium, open the link below:
chrome://net-internals/#dns
and click “Clear host cache“

For Firefox, open the link below:
about:config
then click “I’ll be careful, I promise!“,
and find network.dnsCacheExpiration, set its value to 0 (create one if it didn’t exist).
Now the cache should be flushed, and set network.dnsCacheExpiration back to 3600, or you the cache will not work at all.

Operating system level:

• Windows:
  • ipconfig /flushdns
• Linux:
  Depends on the dns service you are using: 
  • sudo systemd-resolve --flush-caches
  • sudo /etc/init.d/dns-clean restart
  • sudo /etc/init.d/nscd restart
  • sudo /etc/init.d/dnsmasq restart
  • sudo /etc/init.d/named restart
• macOS (> v10.5):
  • dscacheutil -flushcache