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DNS Update Issue

Discussion in 'Bind / DNS / Nameserver Issues' started by sozotech, Sep 26, 2017.

  1. sozotech

    sozotech Well-Known Member

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    We are in the process of migrating accounts from an old cPanel Cloud Linux 5 box to a new Cloud Linux 7. The old server is currently the main DNS servers as well and is clustered with a secondary cPanel DNS server. We clustered the DNS on the new CL7 server with the old CL5 server as well as clustering the server with another cPanel cluster we are running.

    We moved some accounts from the old box to the new box and noticed that the DNS did not update properly to the new IP address. I checked the /var/named/domain.com.db zone file on the old CL5 and it's secondary and sure enough it had the old zone file on it. I checked the other clustered DNS servers and they had the NEW IP. Thinking maybe the zone just failed copying, I did a synchronization from the NEW to OLD and finally the /var/named/domain.com.db did update to the NEW IP however DNS queries to the OLD server and secondary were still reporting the OLD IP. I checked the zone file and it is formatted properly and showing the correct serial number.

    named-checkzone domain.com /var/named/domain.com.db
    zone domain.com/IN: loaded serial 2017092504
    OK

    grep domain.com /var/log/messages
    Sep 25 21:53:29 host named[22901]: zone domain.com/IN/internal: loaded serial 2017092504
    Sep 25 22:57:03 host named[22901]: zone domain.com/IN/external: loaded serial 2017092504

    It looks like the zone is loaded with the correct information, yet

    dig domain.com. @localhost

    still returns the old IP address. I have tried restarting named with no luck.

    I am a little perplexed and am curious if anyone has any ideas what might be going on here?

    Best regards,
    Eric
     
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello Eric,

    Can you reproduce those results with the dig command using a different resolver (e.g. @8.8.8.8 instead of @localhost)?

    Thank you.
     
  3. sozotech

    sozotech Well-Known Member

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    Sorry, it has taken me a while to back this. The funny thing was the domain that was having issues started resolving some time after posting this message without us doing anything.

    Last night we had another ticket come in from a domain that we recently migrated and DNS lookups were failing. The zone was in all of our cluster DNS servers and named-checkzone came back ok. I tried doing a dig directly to the DNS cluster members and it failed.

    I tried manually increasing the serial number and resyncing the domain to the cluster and then restarting named still no luck.

    I checked again this morning with a direct lookup to the DNS cluster members and it worked! It almost seems like there is a delay somehow introduced into the changes. The DNS cluster has over 20,000 zones on it but a restart of named only take a minute or so. Also, other domains migrated don't seem to have the issue.

    I am scratching my head on this. Any ideas?

    Best regards,
    Eric
     
  4. cPanelMichael

    cPanelMichael Forums Analyst
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    Hi Eric,

    Feel free to open a support ticket using the link in my signature if you'd like us to take a closer look.

    Thank you.
     
  5. sozotech

    sozotech Well-Known Member

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    Thanks. Would I open the ticket on the cPanel server in question or on the DNS Cluster server? I assume the DNS cluster but I'm not sure.
     
  6. cPanelMichael

    cPanelMichael Forums Analyst
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    You can open the ticket for the hosting server that's linked to the cluster.

    Thank you.
     
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