What Is DNS Server Cache?


Heather Bennett

What Is DNS Server Cache?

The Domain Name System (DNS) is a fundamental part of the internet infrastructure, responsible for translating domain names into IP addresses. When you enter a URL in your web browser, the DNS server retrieves the corresponding IP address so that your browser can establish a connection to the correct web server.

One important aspect of DNS is caching. DNS servers often cache information to improve performance and reduce network traffic.

When a DNS server receives a request for a domain name, it first checks its cache to see if it has the corresponding IP address stored locally. If it finds a match, it can quickly provide the answer without having to query other DNS servers.

Benefits of DNS Server Cache

  • Improved Performance: By caching DNS information, servers can respond faster to subsequent requests for the same domain name since they don’t need to perform an extensive search each time.
  • Reduced Network Traffic: Caching reduces the number of requests that need to travel across networks, which helps reduce congestion and improves overall network efficiency.
  • Decreased Dependency on External Servers: With cached information, DNS servers can still provide IP addresses even if they are temporarily unable to reach external servers.

TTL and Cache Expiration

DNS caching is not permanent; cached information has an expiration time set by the Time-to-Live (TTL) value specified by the authoritative DNS server. The TTL indicates how long the cached information remains valid before it needs to be refreshed from the authoritative source.

Caching also depends on factors such as network configuration and server settings. Some ISPs or organizations may enforce their own DNS caching policies, which can override the TTL value set by the domain owner.

Clearing DNS Cache

If you encounter DNS issues or need to update DNS records, it may be necessary to clear the DNS cache. The process for clearing the cache varies depending on the operating system and browser you are using.

Here are a few common methods:

  • Windows: Open Command Prompt and type “ipconfig /flushdns” to clear the local DNS cache.
  • MacOS: Open Terminal and enter “sudo killall -HUP mDNSResponder” to flush the DNS cache.
  • Linux: Use the command “sudo systemctl restart NetworkManager” or “sudo service network-manager restart” to restart the network manager, which will clear the DNS cache.


The DNS server cache plays a crucial role in improving performance and reducing network traffic. By storing frequently accessed information locally, DNS servers can provide faster responses and enhance overall browsing experience. Understanding how caching works helps both end-users and system administrators troubleshoot issues related to domain name resolution.

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