Dries Buytaert

Explanation

rel="shortlink" specifies a shorter URL for the current page, to be used in space constrained interfaces and/or for manual entry.

max-age specifies the maximum amount of seconds a page is considered valid. The higher max-age, the longer a page can be cached.

This Expires date is in the future: the page can be served from a cache. The page is set to expire in 299 seconds. At that point, caches should be refreshed.
Notice Because there is a Cache-Control header with a max-age and/or s-maxage directive, the Expires header will be ignored. Consider removing Expires to save bandwidth and processing power.

The Host-Header is a non-standard header often used in setups with a reverse proxy or CDN. It typically preserves the original Host header sent by the client, while the standard Host header may be modified to route the request to the correct backend server. This allows the backend to know the original hostname requested by the client, which can be crucial for proper request handling in multi-domain environments.

The Endurance Page Cache is a WordPress plugin developed by Bluehost. Bluehost automatically installs it on all WordPress sites to add basic file-based caching to WordPress; it turn pages generated by WordPress into static HTML files.

The Vary header specifies a list of headers that must be considered when caching responses. For a cached response to be used, these headers must match between the cached response and the new request. This ensures that the appropriate version of a resource is served based on factors like language, encoding, or device type.
Notice Varying on user-agent can lead to low cache efficiency due to the high number of unique user agents. Only use this if you're serving significantly different content based on user agent.

The type of the message body, specified as a MIME type.

The date and time at which the request was made. A browser uses it for age calculations rather than using its own internal date and time; e.g. when comparing against Max-Age or Expires.

missing Add a Strict-Transport-Security header. The Strict-Transport-Security header or HSTS header is used to instruct browsers to only use HTTPS, instead of using HTTP. It helps enforce secure communication.

missing Add a Content-Security-Policy header. The Content-Security-Policy header helps browsers prevent cross site scripting (XSS) and data injection attacks.

missing Add a Referrer-Policy header. When a visitor navigates from one page to another, browsers often pass along referrer information. The Referrer-Policy header controls how much referrer information a browser can share. This is important to configure when private information is embedded in the path or query string and passed onto an external destination.

missing Add a Permissions-Policy header. Restrict access to device features like the camera, microphone, location, accelerometer and much more.

missing Add a Cross-Origin-Embedder-Policy to specify how this page can be loaded by cross-origin resources.

missing Add a Cross-Origin-Opener-Policy header to opt-in into better browser isolation.

missing Add a Cross-Origin-Resource-Policy header to specify who can load this page.

missing Add a X-Frame-Options header. The X-Frame-Options header prevents this URL from being embedded in an iframe. This protects against clickjacking attacks. Alternatively, set a Content-Security-Policy header with a frame-ancestor directive.

missing Add a X-Permitted-Cross-Domain-Policies header to prevent Flash, Adobe Reader and other clients from sharing data across domains.