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  • 1.  DNS resolution issues EX3400

    Posted 01-13-2022 13:43
    Using Juniper EX3400 switches with Mist Wired Assurance.  All of a sudden some of them stopped communicating with the cloud.  It looks like they are not resolving the DNS names.
    Name servers are setup in the switch:
    set groups top system name-server 208.67.222.222
    set groups top system name-server 8.8.8.8​


    This command fails.

    show host google.com


    Below passes

    show host server 8.8.8.8 google.com


    Doing a TCPDump shows switch is trying to use 127.0.0.1 instead of the configured name server:

    Reverse lookup for 10.26.193.18 failed (check DNS reachability).
    Other reverse lookup failures will not be reported.
    Use <no-resolve> to avoid reverse lookups on IP addresses.
    
    17:58:53.074864 Out IP truncated-ip - 21 bytes missing! 10.26.193.18.60646 > 127.0.0.1.domain:  8585+[|domain]


    Running 20.4R3.8.  Any ideas will be greatly appreciated.
    Thank you



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    MOHAMMAD ALI
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  • 2.  RE: DNS resolution issues EX3400

     
    Posted 01-13-2022 17:16
    Do you have 'apply-groups top' configured?


  • 3.  RE: DNS resolution issues EX3400

    Posted 01-14-2022 05:31
    Yup that is there.

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    MOHAMMAD ALI
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  • 4.  RE: DNS resolution issues EX3400

    Posted 01-14-2022 16:39
    Hi Mohammad,
    I had the similar problem with DNS , I slow this issue when I used template from Mist management see figure. the Mist periodically rewrite local config, maybe this is reason for your problem. 



  • 5.  RE: DNS resolution issues EX3400

    Posted 01-14-2022 19:49
    Let me double check that.  I don't think that is how we are setting up the name servers.

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    MOHAMMAD ALIMOHAMMAD ALI
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