Technical Tip: DNS Server shows Unreachable or high latency in GUI Dashboard even though it is pingable from FortiGate

[jhussain_FTNT]

Description	This article describes how the DNS latency showing in the GUI dashboard is calculated internally.
Scope	FortiGate.
Solution	The DNS server status for FortiGuard or the internal DNS server IP address shows Unreachable or high latency, even though FortiGate can ping to the DNS server IP address without any latency. The DNS query latency is based on when FortiGate system DNS sends a query, which will record the time sent. When a query response is received, the time received will also be recorded. FortiGate calculated the latency (weighted 3:7) of the server based on this value. If there is no DNS response packet received or failed, FortiGate shows the status unreachable. The latency value is not updated, if FortiGate does not query the server since there are no transactions of packets. Note:  To verify if high latency is due to DNS protocol, refer to the following documents for more information: Technical Tip: High latency on FortiGuard DNS serv... - Fortinet Community   Technical Tip: DNS server on FortiGate caused Fort... - Fortinet Community