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Rhiyadi_357606's avatar
Rhiyadi_357606
Icon for Nimbostratus rankNimbostratus
Mar 22, 2019

DNS Resolver

i have an issue this GTM cant reached ip dns server

 

<<>> DiG 9.9.6-P1 <<>> @ ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached

 

I tried it on CLI the F5 GTM

 

anyone can fix it? thanks

 

application delivery
BIG-IP DNS
  • youssef1's avatar
    youssef1
    Icon for Cumulonimbus rankCumulonimbus
    Mar 22, 2019

    Hi Rhiyadi,

    Are you sure that you can reach your DNS (route are set correctly and Firewall rules are deployed for DNS access from your GTM).

    So follow this step:

    • open 2 CLI window
    • on the first CLI Window enter this TCPdump capture

    Withi this capture you will see all your dns request:

    tcpdump -s0 -vvv -nni 0.0 port 53

    • on the secon cli window, lunch the following command:

    dig @yourDnsIP www.toto.ch A

    when is the fqdn that you want to resolve.

    Validate that you see the request in the first window and you pass with the right interface. and validate that FW and route are set correctly for this source IP...

    Let me know if you need more details. regards,