X-Azure-Ref
When a request passes through Azure Front Door or Azure CDN, the X-Azure-Ref unofficial response header returns an opaque identifier for diagnostic log correlation and support ticket resolution.
Usage
Azure Front Door and Azure CDN attach a unique identifier to every request passing through the network. This identifier appears in the X-Azure-Ref response header and in Azure diagnostic logs, linking a specific client response to its internal processing path.
The value is an opaque string with no documented internal structure. The token is intended for server-side log correlation and Microsoft support ticket troubleshooting. When a delivery or routing issue occurs, the identifier allows Azure support engineers to locate the exact request in diagnostic logs and trace the full processing chain across Azure edge nodes.
Clients and applications have no reason to parse or decode the value. The string format is internal to Azure infrastructure and serves as a lookup key, similar to how Cf-Ray works for Cloudflare and X-Amz-Cf-Id works for AWS CloudFront.
Values
Opaque request identifier
Microsoft documents the value only as a unique reference string identifying the request. The internal structure has no public specification for decoding, and observed values open with a UTC timestamp followed by an opaque identifier. Each request produces a distinct value.
Example
A typical response from Azure Front Door includes the request identifier. The value is meaningful only to Azure infrastructure.
X-Azure-Ref: 20260224T091445Z-17c9cc7f8d9x2jvmhC1BY10fq000000012z0000000008r7q
A different request through the same Azure network produces a completely different identifier. Logging this value on the origin server allows correlating a specific client request with its Azure edge processing path.
X-Azure-Ref: 20260212T090009Z-r198d8c9676mqndzhC1PARgv1c0000000rmg00000000drta
The reference string exists for traceability. In a support scenario, providing this value to Microsoft enables precise log lookups without needing to supply timestamps or URLs.
X-Azure-Ref: 20260219T072807Z-r1f8558ffbc6zxmzhC1BY1zg6n00000008u000000000a7cs