What is the use of flushdns? Flushdns application scenarios and operation guides

in daily network use, you may have encountered the situation that the domain name is correct but the website cannot be accessed, or the domain name resolution record has just been modified but the page still displays the old content. Most of these problems are related to DNS caching. Flushdns, as a key operation to clean up the DNS cache, can effectively solve such network anomalies. This article will explain the core role of flushdns, common application scenarios, and specific operation steps under different operating systems to help you easily master this practical network debugging skills.

What is the role of flushdns?

to understand the role of flushdns, we must first understand the basic principle of DNS cache, DNS cache is a system or browser to speed up the speed of domain name resolution and storage of temporary records, flushdns is to clear these cache records operation.

1, solve the problem of domain name resolution exception

when the DNS cache stores the wrong resolution records, such as the Internet Protocol Address corresponding to the domain name has been changed, but the cache is still old data, the website cannot be accessed normally. At this time, after flushdns is executed to clear the wrong cache records, the system will re-request the latest resolution information to the DNS server to restore normal network access.

2, speed up the new analysis record effective speed

many webmasters modify the domain name resolution, they will encounter the situation that the new record does not take effect, because the local or operator's DNS cache still retains the old record. Executing flushdns can force the old cache to be cleared, allowing the system to directly obtain the latest resolution records, greatly shortening the effective time of the new resolution, and avoiding the long process of waiting for the cache to expire naturally.

3, improve network access security

some network attacks will guide users to visit phishing websites by tampering with the DNS cache and pointing the normal domain name to the malicious Internet Protocol Address. Executing flushdns in time to clear the cache records that may be tampered with can effectively reduce the risk of such DNS hijacking attacks and ensure the security of network access.

What are the typical application scenarios of flushdns?

flushdns is not only useful when there is a problem with the network. It can play a key role in many daily network operation scenarios. Let's take a look at some of the most common application scenarios.

1. After modifying the domain name resolution, it will take effect quickly

whether the individual webmaster changes the website server, or the enterprise adjusts the resolution record of the mailbox domain name, after modifying the DNS resolution, the local device may still use the old cache record to access the service. Executing flushdns at this time allows the device to get the latest resolution information immediately, without waiting for hours or even longer cache expiration time.

2, solve the problem of abnormal website access

when the website loads slowly, the page cannot be opened, and the wrong content is displayed, after troubleshooting the network connection failure, it is most likely caused by the abnormal DNS cache. Performing the flushdns operation to clear the wrong cache records can directly solve such network access problems in many cases without complicated debugging steps.

3, test the parsing effect of the new website

before the website goes live, the webmaster usually sets the domain name resolution in advance to test the access effect of the website. If flushdns is not executed, the device may use the old cache record, resulting in inaccurate test results. After flushdns is executed, the device will re-obtain the latest resolution record to ensure that the newly set resolution effect is tested.

How does the Windows system execute flushdns?

Windows is currently the most widely used desktop operating system, different versions of Windows flushdns implementation steps are slightly different, but the overall process is roughly the same, the following is the specific operation method.

1. Execute flushdns

via the command prompt

first press the Win + R key combination to open the run window, enter cmd and click OK to open the command prompt. Enter ipconfig /flushdns in the command prompt window, press the Enter key, and when the window shows the prompt "Successfully refreshed DNS resolution cache", it means that the flushdns operation is completed.

2 flushdns

through PowerShell

for Windows 10 and above, you can also use PowerShell to perform flushdns. Press the Win + X key combination, select the Windows PowerShell (Administrator) option, enter ipconfig /flushdns in the window that opens, and press Enter to complete the operation. This method is exactly the same as the command prompt.

Flushdns operation

of Mac and Linux systems

in addition to Windows systems, Mac and Linux are also commonly used operating systems, these two types of systems perform flushdns and Windows methods are different, you need to use the corresponding end point command.

1, flushdns operation steps of Mac system

open the Mac system's launch pad, find the end point application in another folder and open it. Depending on the Mac system version, enter the corresponding command: for macOS 10.10 and above, enter sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder, press Enter and enter the system password to complete the flushdns operation; for older Mac systems, you can enter sudo lookupd -flushcache to perform the operation.

2, Linux system flushdns operation steps

different Linux distributions to execute the flushdns command slightly different, common Ubuntu, Debian and other systems, open the end point after entering sudo systemd-resolve --flush-caches, press enter and enter the password to complete the operation; for the use of nscd service Linux system, enter sudo service nscd restart, by restarting the service to achieve the effect of flushdns.

sum up, flushdns is a key operation to solve DNS cache related network problems. It can clear wrong DNS cache records, speed up the effective speed of new resolution records, and improve the security of network access. Whether it is Windows, Mac or Linux systems, flushdns can be executed with simple commands. When encountering problems such as abnormal domain name resolution and website inaccessibility, you may wish to try to execute flushdns to easily solve various network glitches.