DNS Flush

What is a DNS flush?

DNS flush is the process of manually deleting the temporary entries of a DNS cache. Without a direct intervention in the cache, the entries exist until their defined life span (“time to live”, TTL) has expired.

Generally, the deletion process is completed using system-specific flush DNS command line tools. On Mac, for example, you use Terminal and the appropriate command for the particular version of the Apple system. In Windows, you flush the DNS via CMD, i.e. via the command prompt, and using the command “ipconfig /flushdns”.

What is the DNS cache?

DNS servers are used to convert domain names such as www.example.com into numerical addresses. These “name servers” are contacted by default via the browser each time the corresponding projects are accessed, which slightly increases their loading time and can also lead to a DNS server overload in the case of a high number of visitors. Error messages like “DNS Server Not Responding” are a common and despised consequence.

For this reason, operating systems like Windows and macOS attach their own cache for accessed and resolved addresses – the DNS caches. These save all information that’s relevant for name resolution such as an IP address, host names and protocol versions. Each entry remains valid for a given time. Within this time, corresponding queries are answered directly from the cache without requiring a detour to the DNS server.

Clear the DNS cache: how-to

ECHO ON

ipconfig /flushdns

TIMEOUT /t 3

ipconfig /registerdns

TIMEOUT /t 3

ipconfig /release

TIMEOUT /t 3

ipconfig /renew

TIMEOUT /t 3

netsh Winsock reset

PAUSE