How to clear DNS cache on DD-WRT

Question

How can I clear the DNS cache in DD-WRT on my router?

DD-WRT uses the dnsmasq daemon.

Besides the technically correct answers below, you could power cycle it... — Hayden Thring, Dec 16 '15 at 10:53

Justin Ethier · Accepted Answer · 2012-05-07T02:10:22.807

24

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 to flush out dns cache:

# stopservice dnsmasq
# startservice dnsmasq

edited May 07 '12 at 02:10

answered Feb 25 '11 at 16:28

Justin Ethier

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There is no "sudo" on dd-wrt. There is not /etc/init.d on dd-wrt, nor any equivalent. – WhyNotHugo May 06 '12 at 03:28
Hmm... The code was just a quick example. Maybe I should delete it. Alternatively do you know the correct command for this env? – Justin Ethier May 06 '12 at 13:09
The other answer has the only way that I know of for restarting services on dd-wrt. Not too clean, but I don't know any other way. – WhyNotHugo May 06 '12 at 21:15
1

How about `stopservice dnsmasq` followed by `startservice dnsmasq`? See http://www.barrymorrison.com/tag/dd-wrt/ – Justin Ethier May 07 '12 at 02:08
Hadn't heard about it. Didn't find it after a quick google either. Great job :) – WhyNotHugo May 07 '12 at 06:35
You can do this in one command: `restart_dns` – Jamie Schembri May 16 '13 at 23:09
`dnsmasq` has a `--clear-on-reload` option, which suggests to me that this answer isn't robust. Using **SIGHUP** is best. – James Haigh Apr 20 '14 at 21:55

score 20 · Answer 2 · answered Sep 15 '13 at 14:52

20

killall -1 dnsmasq

Send HUP signal to tell it flush the cache an reread its configuration, thus starting over with a clean slate.

answered Sep 15 '13 at 14:52

limon

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I think using SIGHUP is the cleanest method because the manpage notes it, and `dnsmasq` may not clear the cache on restart. Though I'd have put `# killall -HUP dnsmasq` rather than `# killall -1 dnsmasq` because it is easier to remember/understand. – James Haigh Apr 20 '14 at 21:51
2

Actually it does _not_ cause it to reread its configuration – that part is incorrect – but that doesn't matter for the question because the configuration doesn't need to be reread to clear the cache. – James Haigh Apr 20 '14 at 22:06

score 6 · Answer 3 · edited Feb 29 '12 at 23:50

6

Since there are no init scripts on DD-WRT, I guess this would be the easiest way to restart dnsmasq:

Kill dnsmasq:
```
root@ddwrt6:~# killall dnsmasq
```

Start dnsmasq:

root@ddwrt6:~# dnsmasq --conf-file=/tmp/dnsmasq.conf

edited Feb 29 '12 at 23:50

Gilles 'SO- stop being evil'

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answered Feb 29 '12 at 17:46

ron

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score 2 · Answer 4 · answered Mar 09 '18 at 03:22

2

Restart the dnsmasq service, either from the user interface.

Or from the command line interface via

/init.d/dnsmasq restart

answered Mar 09 '18 at 03:22

sean

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score 2 · Answer 5 · answered Jan 30 '13 at 23:14

2

I've always used:

killall -1 dnsmasq

which has worked fine for me. I'm running some of the newer versions of DD-WRT and

stopservice dnsmasq
startservice dnsmasq

also seemed to work without error or needing sudo...

answered Jan 30 '13 at 23:14

Phil

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score 1 · Answer 6 · answered Sep 15 '22 at 21:41

1

On 21.02 this is what worked.

service dnsmasq restart

answered Sep 15 '22 at 21:41

ki9

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How to clear DNS cache on DD-WRT

6 Answers6