Headers Added by CDN77

In order for the CDN to cache and deliver your files effectively, it adds several headers to HTTP requests to origins and responses to end users.

HTTP Request:

  • Via: This particular header is added when the CDN requests a file from your Origin server. It is quite useful if you need to identify exactly which requests are being made by the CDN to your Origin server.
    An example of what the full header looks like with the string is "Via: cdn77" or "Via 1.1 cdn77". For instance, if you are filtering this information out from your logs, it functions as an identifier.
  • X-Client-Geo-Country: This header includes a two-letter country code based on the IP of the visitor. If the original request was sent from an IP in Germany, the full header would be "X-Client-Geo-Country: DE".
  • X-Forwarded-For + X-Real-IP: This is the IP Address from the TCP connection from which our CDN Edge server received the request. To protect users’ personal data, we anonymize the last octet in the IP and replace it with a trailing zero. For example, if the IP address received from the TCP connection was, the anonymized IP will be

HTTP Response:

  • X-77-POP: This header is used to identify the geographical location of the CDN77 edge that handled the request and delivered the content (e.g. pragueCZ).
  • X-77-Age: This header gives you information about how long your file has been in the CDN77 cache (time in seconds). It is only added if the header "X-Cache" results in a cache HIT.
  • X-77-Cache: The entry of this header determines the following:
    HIT - The response was delivered from the cache and directly delivered by the CDN edge.
    MISS - The requested content was not found in the cache and the requested content was fetched from the origin server.
  • X-77-NZT + X-77-NZT-Ray: Internal headers used for debugging