====== Networking - DNS - Clear DNS Cache ======


===== Flush Bind Server DNS Cache =====

A caching BIND server obtains information from another server (a Zone Master) in response to a host query and then saves (caches) the data locally.

All you have to do is restart bind to clear its cache:

<code bash>
/etc/init.d/named restart
</code>

You can also use **rndc** command as follows to flush out all cache:

<code bash>
rndc restart
</code>

or

<code bash>
rndc exec
</code>

BIND v9.3.0 and above will support flushing all of the records attached to a particular domain name with **rndc flushname** command.

In this example flush all records related to sharewiz.net domain:

<code bash>
rndc flushname sharewiz.net
</code>

It is also possible to flush out BIND views. For example, lan and wan views can be flushed using the following command:

<code bash>
rndc flush lan
rndc flush wan
</code>

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===== Flush dnsmasq DNS Cache =====

dnsmasq is a lightweight DNS, TFTP and DHCP server.

It is intended to provide coupled DNS and DHCP service to a LAN.

Dnsmasq accepts DNS queries and either answers them from a small, local, cache or forwards them to a real, recursive, DNS server.

This software is also installed many cheap routers to cache DNS queries.

Just restart the dnsmasq service to flush out dns cache:

<code bash>
sudo /etc/init.d/dnsmasq restart
</code>

or

<code bash>
service dnsmasq restart
</code>


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===== Flush nscd DNS Cache =====

Nscd caches libc-issued requests to the Name Service. If retrieving NSS data is fairly expensive, nscd is able to speed up consecutive access to the same data dramatically and increase overall system performance. Just restart nscd:

<code bash>
sudo /etc/init.d/nscd restart
</code>

or

<code bash>
service nscd restart
</code>

or

<code bash>
service nscd reload
</code>

----


===== Flush Mac OS Sierra DNS Cache =====

<code bash>
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder
</code>

----

===== Flush Mac OS X DNS Cache =====

<code bash>
sudo dscacheutil -flushcache
</code>

If you are using OS X 10.5 or earlier try the following command:

<code bash>
lookupd -flushcache 
</code>

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===== Flush Ubuntu DNS Cache =====

<code bash>
sudo systemd-resolve --flush-caches
</code>

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===== Flush Windows DNS Cache =====

<code bash>
ipconfig /flushdns
</code>

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