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Email from cPanel saying that "Some of the server's DNS resolvers failed to respond"

Discussion in 'Bind/DNS/Nameserver' started by Outlier, Mar 12, 2018.

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  1. Outlier

    Outlier Member

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    I started getting an email with the subject "Partial DNS resolver failure" and it says that "Some of the server's DNS resolvers failed to respond". It lists 2 DNS resolver addresses. One of them is "Normal" and the other is "Unreliable". This is the first time I've ever received such an email. I haven't made any recent changes to the website or server (which has been up for about a year) so I'm suspecting this is on my hosting provider's end and/or this might just be temporary. Is this a one time email message or will I continue to get them if the problem persists? In other words, if I wait it out and don't receive any more emails about this, then is it safe to assume the problem corrected itself? Is there a way I can manually check this later on?

    In the meantime, I did add 8.8.8.8 as a tertiary DNS as recommended by Google.
     
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    That message comes from the following script:

    Code:
    /usr/local/cpanel/scripts/check_unreliable_resolvers
    Per it's description:

    This script checks the state of /etc/resolv.conf and can notify when one or more of the nameservers is responding slowly, not responding, unreliable, or otherwise problematic.

    You can manually run the above script as a command to after adding your old resolvers back to the /etc/resolv.conf file to see if it was a temporary issue with the resolver. If it continues to fail, check with your data center or provider to have them determine if there are any issues with the resolver.

    Thank you.
     
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  3. Outlier

    Outlier Member

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    How often does the script check for this? If I don't receive any more email notifications about this, then can I assume it corrected itself?

    I'm relatively new to this and so I'm not sure how to run the script to check manually. Is there a way I can immediately check the DNS by clicking a button in WHM/cPanel? Or how about just entering the url at a DNS checking site like: DNS check tool If it passes at a site like that, can I assume the DNS is ok?
     
  4. cPanelMichael

    cPanelMichael Forums Analyst
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    It runs nightly as part of the cPanel update process. The notification setting itself is controlled via "WHM >> Contact Manager" with the "DNS Resolver Performance Issues" contact type.

    You can safely assume the issue is corrected if you don't receive an additional notification upon the next nightly cPanel update. If you want to run that command manually, we document how to access the server via SSH at:

    SSH Access - Version 70 Documentation - cPanel Documentation

    Thank you.
     
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