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Issue on lab 9.3: Working with CoreDNS

Posts: 22
in LFS258 Class Forum

Here again for another issue on the 9.3 lab: my pod cannot resolve addresses.
After a lot of problems, as described in my past discussion, I recreate the entire cluster, so I'm now able to go ahead, but, reached this lab (9.3) I found another problem. The feeling is that the coredns doesn't work correctly, I restart them, but the problem persists.
I provide here some information and configuration, hoping that someone can help me to identify the problem.

Status of the coredns pods

  1. **kubectl get pods --all-namespaces | grep coredns**
  2. kube-system   coredns-6b4b86d8bf-2r222                   1/1     Running   0          12m
  3. kube-system   coredns-6b4b86d8bf-nqj2m                   1/1     Running   0          12m

my /etc/resolve.conf file on the host

  1. nameserver 127.0.0.53
  2. options edns0 trust-ad
  3. search homenet.telecomitalia.it

/etc/resolve.conf file on nettool pod

  1. nameserver 10.96.0.10
  2. search default.svc.cluster.local svc.cluster.local cluster.local homenet.telecomitalia.it
  3. options ndots:5

Output of the apt update command executed in the pod

  1. root@nettool:/# apt update
  2. Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease         
  3.   Temporary failure resolving 'security.ubuntu.com'
  4. Err:2 http://archive.ubuntu.com/ubuntu focal InRelease                   
  5.   Temporary failure resolving 'archive.ubuntu.com'
  6. Err:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease
  7.   Temporary failure resolving 'archive.ubuntu.com'
  8. Err:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease
  9.   Temporary failure resolving 'archive.ubuntu.com'
  10. Reading package lists... Done        
  11. Building dependency tree       
  12. Reading state information... Done
  13. All packages are up to date.
  14. W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'archive.ubuntu.com'
  15. W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease  Temporary failure resolving 'archive.ubuntu.com'
  16. W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease  Temporary failure resolving 'archive.ubuntu.com'
  17. W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
  18. W: Some index files failed to download. They have been ignored, or old ones used instead.

Log from the coredns pods

  1. **kubectl logs coredns-6b4b86d8bf-2r222 --namespace kube-system **
  2. .:53
  3. [INFO] plugin/reload: Running configuration MD5 = db32ca3650231d74073ff4cf814959a7
  4. CoreDNS-1.7.0
  5. linux/amd64, go1.14.4, f59c03d
  6. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:50073->192.168.1.1:53: i/o timeout
  7. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:53444->192.168.1.1:53: i/o timeout
  8. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:33483->192.168.1.1:53: i/o timeout
  9. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:60055->192.168.1.1:53: i/o timeout
  10. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:45734->192.168.1.1:53: i/o timeout
  11. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:58277->192.168.1.1:53: i/o timeout
  12. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:48417->192.168.1.1:53: i/o timeout
  13. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:45403->192.168.1.1:53: i/o timeout
  14. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:43683->192.168.1.1:53: i/o timeout
  15. [ERROR] plugin/errors: 2 2411310349111695803.1156763954485922933. HINFO: read udp 192.168.140.134:52890->192.168.1.1:53: i/o timeout
  16. [ERROR] plugin/errors: 2 security.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:40467->192.168.1.1:53: i/o timeout
  17. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:55114->192.168.1.1:53: i/o timeout
  18. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:54780->192.168.1.1:53: i/o timeout
  19. [ERROR] plugin/errors: 2 security.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:32826->192.168.1.1:53: i/o timeout
  20. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:34987->192.168.1.1:53: i/o timeout
  21. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:57937->192.168.1.1:53: i/o timeout
  22. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:54716->192.168.1.1:53: i/o timeout
  23. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:37758->192.168.1.1:53: i/o timeout
  24. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:48427->192.168.1.1:53: i/o timeout
  25. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:39343->192.168.1.1:53: i/o timeout
  26. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:55263->192.168.1.1:53: i/o timeout
  27. [ERROR] plugin/errors: 2 security.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:51377->192.168.1.1:53: i/o timeout
  28. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:35208->192.168.1.1:53: i/o timeout
  29. [ERROR] plugin/errors: 2 security.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:45064->192.168.1.1:53: i/o timeout
  30. [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.140.134:36542->192.168.1.1:53: i/o timeout
  31. [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.140.134:59127->192.168.1.1:53: i/o timeout
  32. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:52336->192.168.1.1:53: i/o timeout
  33. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:55511->192.168.1.1:53: i/o timeout
  34. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:58522->192.168.1.1:53: i/o timeout
  35. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:48809->192.168.1.1:53: i/o timeout
  36. [ERROR] plugin/errors: 2 security.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:59664->192.168.1.1:53: i/o timeout
  37. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:44874->192.168.1.1:53: i/o timeout
  38. [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.140.134:50931->192.168.1.1:53: i/o timeout
  39. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:34514->192.168.1.1:53: i/o timeout
  40. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:54530->192.168.1.1:53: i/o timeout
  41. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:45994->192.168.1.1:53: i/o timeout
  42. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:60092->192.168.1.1:53: i/o timeout
  43. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:39119->192.168.1.1:53: i/o timeout
  44. [ERROR] plugin/errors: 2 archive.ubuntu.com.homenet.telecomitalia.it. A: read udp 192.168.140.134:59702->192.168.1.1:53: i/o timeout
  45. [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.140.134:45259->192.168.1.1:53: i/o timeout

Can someone help me to understand where I mistaking?

Thanks in advance!

Andy74

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Comments

  • Posts: 2,451

    Hi @andrea.calvario,

    The issue you are experiencing at this point seems to be related to how your Internet Service Provider operates. It is trying to locate *.ubuntu.com on homenet.telecomitalia.it domain.

    With a simple google search I was able to find a forum post that should provide you with a solution around the DNS issues with telecomitalia. I hope it helps to fix your host's resolv.conf file:

    https://forum.ubuntu-it.org/viewtopic.php?t=428583

    Regards,
    -Chris

  • Posts: 12

    Hi,

    I am experiencing the same issue but the logs don't show the same error related with ISP (until I can understand). Is there something I can do?

    These are the logs from both CoreDNS pods:

    ablo@pablo-VirtualBox:~$ kubectl -n kube-system logs coredns-f9fd979d6-2nd2n
    .:53
    [INFO] plugin/reload: Running configuration MD5 = 823e90b886243896bc5fc311d1fe380f
    CoreDNS-1.7.0
    linux/amd64, go1.14.4, f59c03d
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:36158->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:37468->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:33847->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:58102->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:56101->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:35935->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:49304->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:37233->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:58338->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 5854889205053853889.4992786380578661315. HINFO: read udp 192.168.54.36:56906->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.54.36:44621->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:39647->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:43970->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:49128->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:43476->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:54778->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:35449->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:32906->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.36:39382->192.168.18.1:53: i/o timeout
    pablo@pablo-VirtualBox:~$ kubectl -n kube-system logs coredns-f9fd979d6-sbmlw
    .:53
    [INFO] plugin/reload: Running configuration MD5 = 823e90b886243896bc5fc311d1fe380f
    CoreDNS-1.7.0
    linux/amd64, go1.14.4, f59c03d
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:49955->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:47710->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:36716->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:60608->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:39340->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:57446->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 7925864582003874829.5346898514191063070. HINFO: read udp 192.168.54.39:42763->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.54.39:53249->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.39:42660->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.39:32993->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.54.39:54913->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 security.ubuntu.com. A: read udp 192.168.54.39:35481->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.39:59322->192.168.18.1:53: i/o timeout
    [ERROR] plugin/errors: 2 archive.ubuntu.com. A: read udp 192.168.54.39:48382->192.168.18.1:53: i/o timeout

    As you can see I am working with virtual machines, so far, I haven´t had DNS issues.

    Any information will be appreciated

    Pablo A.

  • Posts: 1,000

    Hello,

    Did you read through the link provided, about checking your VM DNS settings? Are your VMs able to resolve DNS names? Are all of the pods running when you run kubectl get pods --all-namespaces ?

    Regards,

  • Posts: 9

    I had the same issue running on debian 10. I installed the resolvconf package and changed the DNS on the masternode from my local DNS (192.168.1.1) to external DNS (1.1.1.1). And of course a static IP configured on the node. That solved it for me.

  • Posts: 12

    Hi, thank you for your answers. I had already checked the pods out and they were always running. Finally, I followed the RonaldHeirbaut recommendation and downloaded the resolvconf package on the masternode and after that, my pod was able to download the dig and other tools needed for the practice.

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