---
title: Fastly-Debug-Path
summary: null
url: >-
  https://www.fastly.com/documentation/reference/http/http-headers/Fastly-Debug-Path
---

When `Fastly-Debug` is present in a request, this header is attached to the response and contains a summary of the route that a request has taken through the Fastly network.  Here is an example value:

```http
Fastly-Debug-Path: (D cache-lcy1128-LCY 1415969775) (F cache-lcy1130-LCY 1415969775) (D cache-sjc3132-SJC 1415969775) (F cache-sjc3128-SJC 1415969775)
```

Each parenthesized section of the header value represents one server that touched the request, and they are added in the order in which they processed the request.  The syntax is:

```
({serverRole} {serverIdentity} {timestamp})
```

These are:

- `serverRole`: Indicates which role the server is performing in the request.  A `D` here indicates that this server ran the `vcl_deliver` subroutine, while an `F` indicates that it ran the `vcl_fetch` subroutine.  The relationship between these two roles is part of our [clustering](https://www.fastly.com/documentation/guides/vcl/clustering/) process.
- `serverIdentity`: The value of `server.identity`.
- `timestamp`: The unix timestamp in seconds.

In the case of the example above, the end user is likely somewhere near London. Their request arrived at the `LCY` data center and was processed by `lcy1128`. It was forwarded within the cluster to `lcy1130`, which was responsible for fetching the resource. The service was configured to use [shielding](https://www.fastly.com/documentation/guides/concepts/shielding/), so instead of fetching the resource directly from the backend, `lcy1130` forwarded the request to the `SJC` data center (San Jose, California).  In `SJC`, the request was initially handled by `sjc3132` and clustering within that data center forwarded it to `sjc3128`.  It was then fetched from origin.

> **WARNING:** If a response is served from cache, entries in this header beyond the point at which the cache hit was found will describe the path taken when the object was originally cached.  See the `X-Cache` and `Fastly-Debug-TTL` headers to understand cache state.  The timestamps in the `Fastly-Debug-Path` header will differ when the reports are generated as part of different requests.