X-Azure-Ref
The HTTP X-Azure-Ref response header is an unofficial header containing an opaque request identifier assigned by Azure Front Door or Azure CDN.
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, encoded 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.
Note
The "X-" naming convention for HTTP headers, "X" referring to "experimental", has been deprecated and needs to be transitioned to the formal naming convention for HTTP headers.
Values
Encoded request identifier
The value is a Base64-encoded opaque string. Microsoft's documentation confirms the encoding. The internal structure has no public specification for decoding. Each request produces a distinct value.
Example
A typical response from Azure Front Door includes the request identifier as a Base64-encoded opaque string. 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
When Azure processes a request through multiple regions or edge nodes, the identifier encodes the full routing path. 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
Takeaway
The X-Azure-Ref header provides a unique request identifier from Azure Front Door and Azure CDN, used for diagnostic log correlation and support ticket troubleshooting.