Answers: <p>We have not been able to figure out what the problem is or what a solution could be.</p>
  
  <p>The workaround is actually not using the <code>10.0.2.0</code> subnet, so I will add that as an answer as requested in the comments.</p>
  
  <p>If someone finds the real issue and solution here, I will gladly accept that answer though.</p>
  
Answers: CC BY-SA 4.0
Answers: 2020-01-03T22:47:00.703Z
Answers: 2020-01-03T22:47:00.703Z
Answers: Worp
Body: <p>The ultimate problem I am facing is this:</p>
  
  <pre><code>[root@527eb70c04c9 my-service]# ping google.com
  ping: google.com: Name or service not known
  </code></pre>
  
  <p>Inside my container, I can't resolve public domains, although the network is defined as not internal:</p>
  
  <pre><code>networks:
    my-service-network:
      driver: overlay
      internal: false
      attachable: true
      ipam:
        driver: default
        config:
          - subnet: 10.0.2.0/24
  </code></pre>
  
  <p>As soon as I change my subnet from 10.0.2.0 to 10.0.5.0 (really just "NOT" have it be 10.0.2.0) everything works:</p>
  
  <pre><code>networks:
    ess-team-service:
      driver: overlay
      internal: false
      attachable: true
      labels:
        - "group=ess-services"
      ipam:
        driver: default
        config:
        - subnet: 10.0.5.0/24
  
  ping google.com
  PING google.com (172.217.22.14) 56(84) bytes of data.
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=1 ttl=61 time=25.0 ms
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=2 ttl=61 time=22.7 ms
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=3 ttl=61 time=22.5 ms
  ^C
  --- google.com ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2002ms
  rtt min/avg/max/mdev = 22.575/23.462/25.083/1.161 ms
  </code></pre>
  
  <p>A colleague referred to the problem as being caused because Docker's own nameserver is on 10.0.2.0 but I can't find information to back this theory up let alone confirm it.</p>
  
  <p>The main problem is: Sometimes it works. Most times it doesn't but sometimes I can ping google inside the container while the subnet IS 10.0.2.0</p>
  
Comments: CC BY-SA 4.0
Comments: 2019-01-31T06:18:35.307Z
Comments: Might it have to do with dns masquerade mentioned here: https://docs.docker.com/install/linux/linux-postinstall/#dns-resolver-found-in-resolvconf-and-containers-cant-use-it ?
Comments: Worp
Comments: CC BY-SA 4.0
Comments: 2020-01-06T06:51:38.983Z
Comments: Thanks for posting an answer +1
Comments: 030
Tags: <docker><docker-swarm><dns>
Title: Docker Containers fails to DNS resolve on subnet 10.0.2.0/24
UserDisplayName: Worp
ThreadText: # Docker Containers fails to DNS resolve on subnet 10.0.2.0/24
  
  (Asked by: username_0 on 2019-01-29)
  
  The ultimate problem I am facing is this:
  
  ```
  [root@527eb70c04c9 my-service]# ping google.com
  ping: google.com: Name or service not known
  
  ```
  
  Inside my container, I can't resolve public domains, although the network is defined as not internal:
  
  ```
  networks:
    my-service-network:
      driver: overlay
      internal: false
      attachable: true
      ipam:
        driver: default
        config:
          - subnet: 10.0.2.0/24
  
  ```
  
  As soon as I change my subnet from 10.0.2.0 to 10.0.5.0 (really just "NOT" have it be 10.0.2.0) everything works:
  
  ```
  networks:
    ess-team-service:
      driver: overlay
      internal: false
      attachable: true
      labels:
        - "group=ess-services"
      ipam:
        driver: default
        config:
        - subnet: 10.0.5.0/24
  
  ping google.com
  PING google.com (172.217.22.14) 56(84) bytes of data.
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=1 ttl=61 time=25.0 ms
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=2 ttl=61 time=22.7 ms
  64 bytes from fra16s14-in-f14.1e100.net (172.217.22.14): icmp_seq=3 ttl=61 time=22.5 ms
  ^C
  --- google.com ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2002ms
  rtt min/avg/max/mdev = 22.575/23.462/25.083/1.161 ms
  
  ```
  
  A colleague referred to the problem as being caused because Docker's own nameserver is on 10.0.2.0 but I can't find information to back this theory up let alone confirm it.
  
  The main problem is: Sometimes it works. Most times it doesn't but sometimes I can ping google inside the container while the subnet IS 10.0.2.0
  
  **Tags:** docker, docker-swarm, dns
  
  > **Comments:**
  > **username_0**: Might it have to do with dns masquerade mentioned here: https://docs.docker.com/install/linux/linux-postinstall/#dns-resolver-found-in-resolvconf-and-containers-cant-use-it ?  
  > **username_1**: Thanks for posting an answer +1  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2020-01-03. Score: 1 | Accepted answer
  
  We have not been able to figure out what the problem is or what a solution could be.
  
  The workaround is actually not using the `10.0.2.0` subnet, so I will add that as an answer as requested in the comments.
  
  If someone finds the real issue and solution here, I will gladly accept that answer though.
  
  
  ---
  
  