Non HTTP response code: java.net.UnknownHostException from Azure load testing

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Non HTTP response code: java.net.UnknownHostException from Azure load testing

Satya Palathirthapu 0

Greetings, I am attempting to execute a JMeter script within Azure Load Testing; however, it fails with the error message "Non HTTP response code: java.net.UnknownHostException." This script functions correctly on my local machine, where I can successfully conduct the load test. Could you please provide insight into why I am unable to run the same script in Azure Load Testing? Is there a need to configure a proxy, subnet, or any other settings?

Thanks in advance for your help.

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Answer 1

UnknownHostException is a DNS-resolution failure on the Azure-hosted test engine, not an HTTP or proxy response. The local test succeeds because your workstation can resolve and reach the hostname; a default Azure Load Testing engine does not inherit your local DNS, hosts file, VPN, or proxy.

First inspect the expanded JMeter server-name value and uploaded CSV or property files to ensure the engine is not receiving a literal variable or malformed hostname. If the target is publicly reachable, confirm its public DNS record resolves from an unrelated network. If it is private, configure the load test for virtual-network injection into a dedicated subnet that can reach the endpoint. Link the required private DNS zone to that VNet, or configure the VNet’s custom DNS server to resolve the name, and allow DNS plus target-port traffic through NSGs, routes, and firewalls. Re-run one engine in debug mode before scaling out.