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mrSuperEvening
Asked: 2020-11-28 12:41:07 +0800 CST

DNS lookup is sometimes very slow

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So I figured out my problem finally through browser developer tools after weeks of scratching my head why sometimes some page loads are super slow.

I saw that DNS lookup is sometimes really slow (2-3 seconds).

What can I do to fix it? Thank you.

dns

2 Answers

  1. Best Answer

    I had issues with systemd-resolved before. You can do the following:

    1. Try disabling and stopping the systemd-resolved service:

      sudo systemctl disable systemd-resolved
sudo systemctl stop systemd-resolved

    2. In the [main] section of your /etc/NetworkManager/NetworkManager.conf:

      dns=default

    3. Delete the symlink /etc/resolv.conf:

      rm /etc/resolv.conf

    4. Restart NetworkManager:

      sudo systemctl restart NetworkManager

    5. Then you can create /etc/resolv.conf with your preferred DNS server specified in there.

    6. Finally, test and check if you are getting a better performance out if it.

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  2. I had similar problems in the past, with slow or even failing DNS lookups.

    It turned out to be DNS problems most probably related to the "ADSL modem"-ISP combination, as some (but not all) DNS lookups were timing out.

    So, the problems were not related to my Ubuntu OS (either 18.04 or 20.04); the remedy was to simply reboot my ADSL modem.

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