Flush DNS: how to clear DNS cache


Anyone who goes about on the internet gives many traces – even inexperienced browser users probably know this by now. It is because website operators use technology such as cookies or JavaScript applications to register the behaviour of visitors.

The data collected here is used to optimize the website and personalize the content without actively disclosing personal details. In conclusion, many users increasingly rely on ad and JavaScript blockers and proxies or delete history and cookies to end data collection and preserve their privacy.

What is the DNS cache?

DNS servers convert domain names such as www.example.com into numerical addresses that computer systems can process. Unfortunately, these “name servers” are contacted by default via the browser each Time the related 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.

As a result, error messages like “DNS Server Not Responding” are a common and despised consequence.

Like web browsers or name servers from internet service providers, various applications also have their DNS cache for advancing up name resolution.

What data does the DNS cache contain?

The data units or entries in the DNS cache are called resource records (RR) and are represented in ASCII code (in compressed form). The different – partially optional – components comprise the following:

Resource data (rdata): data that represents the record, for example, address or hostnameRecord type: kind of the created entry, e.g. “A”: IPv4 address (decimal value: 1) or “AAAA”: IPv6 address (decimal value: 28)Record name (optional): domain name of the target for which the DNS entry was generatedTime to live (optional): validity time of the resource life in secondsClass (optional): protocol group that the RR relates to (mainly “IN” for internet)Resource data length (optional): value for the size of the resource data

The DNS cache includes IP addresses for the respective domains or hosts and further information specifying it – like the validity period of the record or the relevant protocol group.

Why is a regular DNS flush beneficial?

Hide search behaviour: While cookies, JavaScript, and others primarily carry out the tracking of user behaviour on the internet, the DNS cache still offers a potential target for all data collectors. Based on the listed addresses, including additional information such as the validity period (if given), you can get an approximate overview of your page history.

Security toward Manipulation: You should also clear the DNS cache from Time to Time for security reasons. The knowledge in the cache is practical for delivering web projects – but can immediately become dangerous in the wrong hands. For example, if cybercriminals gain access to the DNS cache, they’re in a position to manipulate the entries and redirect you to inappropriate websites. For instance, DNS poisoning or DNS spoofing is frequently used to obtain sensitive log-in data to online banking. With a DNS flush, you can lead such manipulated records with minimum effort.

Solve technical problems: A DNS flush on macOS, Windows, and others is usually an effective solution if you’re encountering technical issues when accessing web applications. With the updated address data, the link to the web plan will once regularly work as planned.

How to Clear the DNS cache:

There’s no rule about while the perfect moment for a DNS flush is – unless there’s a significant problem that can be done by emptying the cache. The DNS cache should also be cleared quickly if you’re redirected to a website that you didn’t request.

Windows 7: how to flush DNS

As a Windows 7 user, you may operate/run a DNS flush via the command prompt. To apply this, tap on the Windows home button and type “cmd” into the search bar. Then start the command-line tool by clicking or driving enter.

Enter the following command:

ipconfig /flushdns: When you press enter, Windows cleans the DNS cache. You’ll receive the subsequent message confirming that the cache was successfully flushed.Windows 7: ipconfig /flushdns: The flushdns command on Windows 7 can also operate without the space worked here before the slash.Windows 8: operate/run a DNS flush: The command prompt is the tool for a DNS flush on Windows 8. First, open the start menu through the home button and then search utilizing the magnifying glass symbol. Search for “cmd” and pick the command prompt by clicking.Windows 8: search function: Windows 8 commences the search for the coveted term right away. You don’t have to verify your entry manually with entering.

To clear the DNS cache, register the given command:

ipconfig /flushdns: Commence the flushing process by pushing enter. A command-line message will notify you of the success of the DNS flush.Windows 10: how to remove the DNS cache: The command prompt operates in the same way on Windows 10, and the procedure slightly differs from that of Windows 7 and 8: in the first step, use the search function to scan for the command line application cmd.

Search bar on Windows 10

You can locate the command prompt not only through the search but also in the start menu under “Accessories.”

Clean the DNS cache with the command “ipconfig /flushdns”:

Windows 10: DNS flush through the command prompt

The Windows command prompt doesn’t distinguish between upper- and lower-case characters, so your command data can be with or without capitalization.If the process has worked as wanted, then the command prompt reinforces the conclusion of the flush process.

Drive a DNS flush on Linux: how it operates

Linux systems don’t hold a DNS cache by default. The various distributions only offer a function to store DNS information locally using appropriate DNS-clean or dnsmasq. If you utilize one of these services for caching, you have to restrain it from the terminal to remove the cache.

For pdnsd, there’s a concrete, transparent command:

sudo pdnsd-CTL empty-cache

To remove the DNS cache from dnsmasq, DNS-clean, or ncsd, though, you need to restart the respective service completely:

sudo /etc/init.d/dnsmasq restartsudo /etc/init.d/nscd restartsudo /etc/init.d/dns-clean restartUbuntu terminal: restart DNS-clean

You need administrator rights to use DNS caching services in Linux distributions like Ubuntu and clear the cache.

How to flush DNS on Mac

Like Windows, macOS has a blended DNS cache that automatically collects DNS information and should be removed regularly. As objected to the Microsoft systems, though, the command for resetting the cache modifies from version to version. What you need to access into the terminal to set the DNS register back to zero depends on the edition that you’re operating with:

OS X 10.10.4 (Yosemite) and 10.11.0 (El Capitan):

sudo dscacheutil -flushcache;sudo killall -HUP mDNSResponder

macOS 10.12.0 (Sierra):

sudo killall -HUP mDNSResponder

OS X 10.9.0 (Mavericks):

sudo dscacheutil -flushcache;sudo killall -HUP mDNSResponder

OS X 10.10.1 to 10.10.3 (Yosemite):

sudo discoveryutil mdnsflushcachesudo discoveryutil udnsflushcaches