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Andy-didnt-like-uucp's avatar
Andy-didnt-like-uucp
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Aug 06, 2023

F5OS r2800 out-of-box DNS

Hi Guys i'm a bit new to F5OS & need some help. i have fresh unpacked r2800 which i configured with 2 domestic DNSs only in RFC1918. But when i watch on tcpdump i can see chassis queries google DNSs...
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  • Andy-didnt-like-uucp's avatar
    Andy-didnt-like-uucp
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    Aug 08, 2023

    Hi Dario
    in the 1st approach i shouldnt face it as per 

    "Cause

    When there is no dns server configured on host, the docker will use 8.8.8.8 and 8.8.4.4 to forward the dns request from docker containers. This is how docker behaves by design"

    bc i have DNS servers configured :0)
    F5LB01# show system dns
    system dns state search [ <internal-domain-sanitized> ]
    ADDRESS ADDRESS PORT
    ----------------------------
    10.XX.YY.49 - 53
    10.XX.YY.50 - 53

    in the 2nd iteration how i can be sure i've restarted docker?
    Recommended Actions

    As a workaround you can set a fake internal ip which does not exist as dns server as block hole
    Once you have custom DNS configured you need to restart docker