Question

Temporary name resolution failure across docker, ping, apt...

Problem demo

or how ping, docker and apt update all hit the same problem

> ping digitalocean.com
ping: digitalocean.com: Temporary failure in name resolution

>  ocker pull helloworld
Using default tag: latest
Error response from daemon: Get https://registry-1.docker.io/v2/: dial tcp: lookup registry-1.docker.io on [::1]:53: read udp [::1]:40123->[::1]:53: read: connection refused

>  apt update
Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease
  Temporary failure resolving 'security.ubuntu.com'
Err:2 https://repos-droplet.digitalocean.com/apt/droplet-agent main InRelease
  Temporary failure resolving 'repos-droplet.digitalocean.com'
Err:3 https://download.docker.com/linux/ubuntu focal InRelease
  Temporary failure resolving 'download.docker.com'
Err:4 http://mirrors.digitalocean.com/ubuntu focal InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Err:5 http://mirrors.digitalocean.com/ubuntu focal-updates InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Err:6 http://mirrors.digitalocean.com/ubuntu focal-backports InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Reading package lists... Done
Building dependency tree       
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal-updates/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal-backports/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch https://download.docker.com/linux/ubuntu/dists/focal/InRelease  Temporary failure resolving 'download.docker.com'
W: Failed to fetch https://repos-droplet.digitalocean.com/apt/droplet-agent/dists/main/InRelease  Temporary failure resolving 'repos-droplet.digitalocean.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

I HAVE added 2 more nameservers, 1.1.1.1 and 8.8.8.8, which I can ping. By this I mean:

> vim etc/netplan/50-cloud-init.yaml

network:
    version: 2
    ethernets:
        eth0:
            addresses:
            - 143.110.178.152/20
            - 10.47.0.5/16
            gateway4: 192.75.31.155

            match:
                macaddress: 0a:ee:7a:c3:93:aa
            nameservers:
                addresses:
                - HERE I"VE ADDED 4 8s, line below, 4 1s
                - 67.207.67.2
                - 67.207.67.3
                search: []
            set-name: eth0

It did not help. I have modified /etc/hosts to add IP for docker registry. This yielded invalid cert message:

>  docker pull helloworld
Using default tag: latest
Error response from daemon: Get https://registry-1.docker.io/v2/: x509: certificate is valid for *.setupdev.abaris.com.br, *.abaris.com.br, not registry-1.docker.io

Ideas are more than welcome. I’m now looking into firewall config, but I have not changed it or dabbled in it, so I’m not particularly hopeful. Also, Networking tab in config panel indicated it’s not a good lead.


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alexdo
Site Moderator
Site Moderator badge
July 10, 2023

Heya,

In addition to that, you might want to check if the resolv.conf file is configured correctly. You can try to temporarily set the nameserver directly in the /etc/resolv.conf file by adding the following lines:

nameserver 8.8.8.8 nameserver 1.1.1.1

This should override any DNS settings on the server. However, note that this is only a temporary solution. If this works, it means there’s likely an issue with how the DNS is configured in netplan.

If that doesn’t help, there might be a more complex issue happening and further troubleshooting might be necessary.

For your Docker related concerns, it’s possible that Docker is not using the correct DNS. Docker typically uses the same DNS as the host machine, but this can be manually set as well. Refer to Docker’s official documentation on working with network commands for more information.

For more instruction on networking and DNS configuration, you can explore our documentation in this link.

Hope that this helps!

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