Can an ETag be changed with a 304 response?

Question

• Browser makes request with header If-None-Match: "123"
• Server returns 304 response with header ETag: "555"

Will subsequent browser requests for that url contain the header If-None-Match: "123" or If-None-Match: "555"? Is this behavior consistent between browsers?

Answer 1

It appears that Chrome will not update the If-None-Match header when the 304 response returns a new ETag header. The browser continues using the If-None-Match: "123" on subsequent requests, even if the server returned ETag: "555" with a 304 response.