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gokiwi64
gokiwi64
New Member
January 28, 2025
Question

FortiGate DNS Settings Issues

  • January 28, 2025
  • 3 replies
  • 1258 views

Hello All,

On our FortiGates under Global/Network/DNS we specify our own DNS Servers but they are almost always in red (high latency) or showing as unreachable.

We are only using plain old DNS (udp/53).

We have never been able to work out why (it happens on both our 600F and 100F) and what we need to do to fix it , I have no idea if there is some config somewhere that's missing etc etc.

Hoping the experts out there can help ?

 

Regards

 

 

3 replies

AEK
SuperUser
AEK
SuperUser
January 29, 2025

Hi

Is you DNS resolution fine when you send the query to the configured DNS servers?

Does you FGT resolve in acceptable time?

AEK
    josull
    josull
    New Member
    October 31, 2025

    We are having the exact same issue. Did you manage to resolve it?

    esalija
    Staff
    esalija
    Staff
    October 31, 2025

    Hi @gokiwi64 

     

    To address the issue of high latency or unreachable DNS servers on your FortiGate devices, follow these steps:

    1. Ensure that the DNS servers specified are correct and reachable from the FortiGate.
    You can use the "# exec ping" command to test connectivity to the DNS servers
    2. Since you are using plain DNS (UDP/53), ensure that DNS over TLS or DNS over HTTPS is not enabled, as these require different ports (TCP/853 for DoT and TCP/443 for DoH).
    3. Use the command " # diagnose test application dnsproxy 2 "to check the latency and status of the DNS servers.
    This will provide insights into whether the servers are responding slowly or not at all.

     

    Best regards,

    Erlin

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