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Default HTTP Response Headers

Overview

This document describes default response headers that EdgeOne passes to the client. These headers follow the origin unless there are custom HTTP headers.





Default HTTP response headers

EdgeOne adds the following default HTTP response headers to responses to the client.

EO-Cache-Status

EO-Cache-Status is used to indicate whether the current Client-initiated requests hit the Cache or not, with the following values:
EO-Cache-Status: HIT: Indicates that the requested resources hit the Cache on the EdgeOne node and the Cache is not expired, directly responded by the node to the user requests.
EO-Cache-Status: MISS: Indicates that the requested resources did not hit the Cache on the EdgeOne node, or hit the Cache but the Cache is expired, the node performs origin-pull verification, the origin file is updated and responded with a 200 status code, the node needs to origin-pull the resources.
EO-Cache-Status: RefreshHit: Indicates that the requested resources hit the Cache on the EdgeOne node, but the Cache is expired, the node performs origin-pull verification, the origin file is not updated and responded with a 304 status code, the node continues to use the Cache to respond to user requests.

Server

This header indicates the server name. The header value depends on the service that the Web Server is built on. By default, this header follows the origin response (if exists). Otherwise, the EdgeOne node adds this header with the value of Server:TencentEdgeOne. For more information, see Server.
Values of Server header for different origin types:
Cloud Object Storage (COS) origin: Server: tencent-cos
Cloud Virtual Machine (CVM) origin: Server: nginx, Server: apache, Server: tomcat, or Server: Microsoft-IIS
Cloud Load Balancer (CLB) origin: Server: openresty

Date

The value of the Date header is the current time of the EdgeOne node server. For more information, please refer to Date.
For instance: Date: Sat, 07 Jan 2023 14:15:52 GMT.

Connection

This header indicates how a persistent connection is handled during the communication between the client and server. By default, this header follows the origin response (if exists). Otherwise, EdgeOne sets the header based on the following rules:
HTTP/2 and QUIC requests: This header is not added.
HTTP 1.0 requests w/o KeepAlive option: The header is set to Connection:close.
**Origin response does not contain content-length and transfer-encoding**: This header is set to Connection:close.
In other cases, the header is set to Connection:keepalive.
For more information, see Connection.

Alt-Svc

Alt-Svc stands for Alternative-Service. It lists the alternative access methods of the site. This header is commonly used for backward compatibility with previous protocols after updating to a new one, such as QUIC. If you enable HTTP/3 (QUIC) for a domain name, this header is added to the HTTP response header by default. For more information, see Alt-Svc.

EO-LOG-UUID

It carries the unique identifier of the request. When an access exception occurs, you can locate the problem by querying logs with this UID.

Example: EO-LOG-UUID: 4105283880544427145.