Technical Tip: High latency on FortiGuard DNS serv...

FortiGate

FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.

Article Id 219170

Description

The article describes how to solve the high latency when FortiGuard DNS server is used.

Scope

FortiGate.

Solution

Starting from firmware version 7.0 onwards, the 'Use FortiGuard Servers' DNS will be using the DNS over TLS by default, but some of the site will be having high latency even unreachable to FortiGuard DNS.

And the DNS Protocols will be greyed out on GUI as shown below:

To change the different method to reach FortiGuard DNS, for example, change default TLS(TCP/853) to DNS (UDP/53), it is possible to change using CLI command below:

# config system dns
set protocol cleartext <----- Default is dot(DNS over TLS).

end

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Technical Tip: High latency on FortiGuard DNS servers