NSX UI generates the alarm "Forwarder Upstream Server Timeout"

Products

• VMware NSX

Issue/Introduction

• There were planned/Unplanned changes in the physical network from the ISP.
• In the NSX UI, you receive an alarm."Forwarder Upstream Server Timeout".
• VMs connected to the segment are unable to query the DNS.
• In var/log/dns/failed-query.log on the Edge node logs we see the following error:

<edge_hostname> dnsmasq_########-####-####-####-############ - -  Failed DNS Query. record_type: 1, address: ########.####.### , error_type: TIMEOUT, client_ip: <ip_address>, forwarder_ip: <ip_address> source_ip: <ip_address>, upstream_server_ip:<ip_address>, time_spent: 65, error_message: None,,

Environment

VMware NSX

Cause

DNS queries to the configured upstream server are timing out. This indicates a lack of response from the upstream DNS server or a potential network path issue.

Resolution

Verify with the physical network or ISP team whether any planned or unplanned network changes have occurred and ensure upstream connectivity and DNS reachability are restored.

Additional Information

Related Articles.

Forwarder upstream server timeout Alarm