dns_server_failure while accessing web site via the Cloud SWG

Products

• Cloud Secure Web Gateway - Cloud SWG

Issue/Introduction

Browser indicates Network Error (dns_unresolved_hostname) while accessing the web site via the Cloud SWG. In the Proxy Log the error "dns_server_failure" is observed under the verdict with the status code 503:

Cause

The host name does not exist and cannot be resolved by the Cloud SWG proxy. Use the public independent DNS tools such as dnschecker to verify the DNS resolution of the affected domain. 

Resolution

Make sure host name in the URL is correctly indicated. Contact web site admin to investigate the issue further.

Also check Error: "dns_lookup_failure" with Cloud SWG (WSS)