How can I flush the DNS on Ubuntu 17.04?

Question

I seem to have a few DNS issues at the moment since upgrading to 17.04 from 16.10 and went to flush the DNS but I can't find how to.

Can anyone tell me please?

I ran into the same thing yesterday. This took care of my issue: https://superuser.com/a/1200745 — Clay Oster, Apr 19 '17 at 14:01
Possible duplicate of [How do I clear the DNS cache?](https://askubuntu.com/questions/2219/how-do-i-clear-the-dns-cache) — Chai T. Rex, Apr 22 '17 at 00:50
I have removed the solution part from the question. But you can find it [here](https://askubuntu.com/revisions/906476/2). Please post the solution part in the "Your Answer" field below. It's completely okay to answer your own question and accept your answer. Also please [don't add "SOLVED" tag to title](https://meta.stackexchange.com/questions/116101/is-it-ok-to-add-solved-to-the-title-of-a-question). — pomsky, Mar 31 '18 at 10:41
I've found nothing works short of rebooting the system and walking on egg-shells — ThorSummoner, Feb 11 '19 at 17:47
If you are using Chrome and are having cache issues, it'll also help to clear Chrome's dns cache chrome://net-internals/#hsts — Peter Chaula, Jun 22 '19 at 11:34

Dmitry Sidorenko · Accepted Answer · 2017-04-27T09:43:06.647

124

You may use this command: sudo systemd-resolve --flush-caches

To verify that flush was sucessfull, use: sudo systemd-resolve --statistics

Sample output:

Cache
  Current Cache Size: 0
          Cache Hits: 101
        Cache Misses: 256

edited Apr 27 '17 at 09:43

answered Apr 26 '17 at 14:51

Dmitry Sidorenko

This answer improves on the previous one so I have marked it as the one true answer. – dibs Apr 26 '17 at 21:54
17

When I run `sudo systemd-resolve --flush-caches`, I get `systemd-resolve: unrecognized option '--flush-caches'`. – Nathan Friend Jan 19 '18 at 17:35
1

Same as @NathanFriend - Checking the --help output, this subcommand was removed in 17.10 – Routhinator Feb 27 '18 at 22:48
3

I'm running Ubuntu 18.04 and the subcommand is there. – the_drow Jun 05 '18 at 14:48
@NathanFriend same thing for 16.04 – Hastig Zusammenstellen Aug 10 '18 at 23:32
1

Not there in Ubuntu 16.04 – adamczi Nov 27 '18 at 10:41

score 34 · Answer 2 · answered Apr 21 '17 at 22:24

34

This command should restart the local name service and flush the local DNS cache:

systemctl restart systemd-resolved.service

There is probably a way of getting it to just flush the cache instead of restart, but restart suited my purposes.

answered Apr 21 '17 at 22:24

tigs001

This seems like the only way to clear everything to 0 when running `--statistics` immediately after. On Ubuntu 18 – sledgeweight Oct 12 '18 at 19:45

dunderrrrrr · Answer 3 · 2018-03-31T08:28:40.817

0

Maybe thats what youre looking for.

Installation

$ git clone git@github.com:dunderrrrrr/dnscache.git
$ cd dnscache/
$ sudo cp dnscache /usr/local/bin/
$ sudo chmod +x /usr/local/bin/dnscache

Usage

There are two arguments that can be passed to the script, clear or stats. Both of them should be self explanatory.

$ sudo dnscache clear
DNS cache has been cleared!
[...]
Cache
  Current Cache Size: 0
[...]

edited Mar 31 '18 at 08:28

answered Mar 28 '18 at 20:10

dunderrrrrr

3

Could you please expand the answer and maybe add installation process and usage? – pomsky Mar 28 '18 at 23:02
It's all on github. – dunderrrrrr Mar 31 '18 at 08:25
I agree, but link-only answers are not considered as answers on [Stack Exchange sites](https://meta.stackexchange.com/questions/225370/your-answer-is-in-another-castle-when-is-an-answer-not-an-answer). Thanks a lot for expanding your answer. – pomsky Mar 31 '18 at 10:35
4

It's only running `systemd-resolve --flush-caches` then `systemd-resolve --statistics`. : https://github.com/dunderrrrrr/dnscache/blob/master/dnscache – Ricky Notaro-Garcia Jun 28 '18 at 15:00
Well, thats the point. It's much faster typing `sudo dnscache clear`. Time is money, right. – dunderrrrrr Jul 08 '18 at 10:06
1

seems like a cheap attempt to farm rep. – Phil Feb 18 '19 at 21:48

3 Answers3