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Strange DNS resolver issue on VSX switches

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  • 1.  Strange DNS resolver issue on VSX switches

    Posted Jan 25, 2024 12:50 PM

    Hi 

    We have some redundant VSX stacks of CX8360 running 10.10.1090 and we have issues with connectivity to central from the MGMT interface.
    My working theory is that the problem is caused by failed DNS lookups (see below)

    The interface is configured with a static IP and a static gateway:

    interface mgmt
        no shutdown
        ip static 172.26.0.5/16
        default-gateway 172.26.0.1

    The config also contains these DNS entries:

    ip dns server-address 172.16.10.7 vrf mgmt
    ip dns server-address 172.24.10.5 vrf mgmt
    ip dns server-address 172.16.10.5 vrf mgmt

    But when I login to the switch any attempt at name resolution fails with "temporary name resolution failure" when trying to ping names from MGMT. 

    The MGMT vrf and interface has internet connectivity as I can ping 8.8.8.8 with the command "ping 8.8.8.8 vrf MGMT"
    The same command can also ping all of the DNS servers.

    I tried using start-shell and have a look at /etc/resolv.conf, but that contains no DNS servers - regardless if I enter some into the config without the appended "vrf mgmt".
    On my other CX switches all entered DNS servers in the config ends up in /etc/resolv.conf

    Any idea what causing the DNS resolver issue (and likely the central connectivity issue)?

    Cheers.



  • 2.  RE: Strange DNS resolver issue on VSX switches

    Posted Jan 26, 2024 05:02 AM
    You could try :
    interface mgmt
        no shutdown
        ip static 172.26.0.5/16
        default-gateway 172.26.0.1
        nameserver 172.16.10.7 172.24.10.5
    (only two is allowed)



    ------------------------------
    Arne Opdal
    ------------------------------

    Original Message


  • 3.  RE: Strange DNS resolver issue on VSX switches

    Posted Jan 26, 2024 11:05 AM

    -


    Original Message


  • 4.  RE: Strange DNS resolver issue on VSX switches

    Posted Jan 26, 2024 11:37 AM

    Excellent - That did the trick :-)

    Thank you very much.


    Original Message