Tag: DNS recursive server

What is the purpose of DNS cache?What is the purpose of DNS cache?

In this post, you will discover the primary purpose of the DNS cache and how you can delete it. Let’s begin.

DNS cache – definition

The DNS cache is a type of temporary cache memory used by devices and DNS resolvers to store all previously used DNS records for the searched domain names. For example, the IP addresses of domain names and subdomains, data for their services, information about their email server, verification and authentication information, and so on are all contained in these records. Based on each DNS record’s TTL (Time to Live) value, the data will be saved in this DNS cache.

How does it work?

It works in a simple way. A DNS lookup is triggered whenever a user requests a domain name. Then the user’s device will initially look in the DNS cache built into its operating system (OS). It’s a database where distinct DNS records and their TTL values are stored. As previously stated, that TTL is established by the domain’s DNS administrator. The needed DNS entries can be found immediately there if the TTL hasn’t expired. The request will be fulfilled, and the domain will load extremely quickly. However, if the TTL has already passed, a new lookup will require additional time for the entire process to repeat.

This indicates that a DNS recursive server will accept the user’s request and request DNS records from other servers. First, it will query the root server, which will lead to the particular TLD server that should be searched, and then the recursive will be sent to the authoritative name server, which will finally supply DNS data (records).

The information will be transmitted to the user’s browser so that the domain can be loaded. Those data will be cached in the recursive server’s DNS cache, and the user’s device (computer, tablet, or mobile) will have access to them for as long as their TTLs allow.

Could you delete a DNS cache?

Yes, you can do it yourself. The clearing method varies depending on your operating system and browser, which may have its own DNS cache.

  • On Windows

So, first, find the Command Prompt and open it. Then type the following command: 

ipconfig /flushdns

Then you have to see a confirmation message. This is because the DNS has now been cleared.

  • On Linux

Launch the Terminal. Then run the following command:

sudo systemd-resolve –flush-caches

After that, type your sudo password and hit Enter. The DNS cache is deleted!

  • On macOS

First, open the Terminal. Then type the following command:

sudo killall -HUP mDNSResponder

After that, type your password and press Enter. Ready!

Okay, we see how to clear the DNS cache on different operating systems. Now, let’s see how to do it in different browsers:

  • Google Chrome/ Edge/ Opera

Chrome:/net-internals/#dns – copy this line. Then paste the line into your browser’s address bar. Enter your password. So now, on the page, look for “Host resolver cache” and then click “Clear host cache.” Ready!

  • Safari

In Safari, you can delete your cache by a different method type. First select “Advanced” from the “Preferences” menu. Next, look for “Show develop menu” in the toolbar there. Then find “Develop,” followed by “Empty Caches.” Ready!

Conclusion

In conclusion, we can agree that the DNS cache is a helpful tool for speeding up and streamlining the DNS resolution process. However, if necessary, you can delete it by following the steps above, depending on your operating system.