Technical Tip: FortiGates in Belgium unable to resolve hostnames when using OpenDNS as DNS servers

FortiGates deployed in the Country of Belgium might face DNS resolution issues when they are configured to use OpenDNS as their DNS servers.

config system dns
    set primary 208.67.222.222
    set secondary 208.67.220.220
end

When trying to resolve names, the FortiGate may display the following error:

fgt01 # exe ping fortinet.com
unable to resolve hostname

A sniffer will show that the DNS server is responding to the DNS query with the following message:

Effective.April.11,.2025:.Due.to.a.court.order.in.Belgium.requiring.the.implementation.

of.blocking.measures.to.prevent.access.within.Belgium.to.certain.domains,

.the.OpenDNS.service.

is.not.currently.available.to.users.in.Belgium"

diagnose sniffer packet any "host 208.67.222.222 or host 208.67.220.220" 6 0 l

The solution is to switch to other DNS servers, such as FortiGuard DNS servers.

config system dns
    set primary 96.45.45.45
    set secondary 96.45.46.46
end