Chrome host overrides are not supported on SPDY-enabled requests.
Catchpoint’s Chrome monitor tests run on Chromium, the open-source project that forms the basis of Google Chrome. When attempting host overrides using Request Headers, the response header will remain unchanged if the site is using SPDY.
Example:
Below is part of a request header from a web test using the chrome monitor against https://www.google.com. It has SPDY enabled and has a host override to amazon.com:
Note that the header remained unchanged and went to google.com instead of amazon.com.
Workaround:
In order to change the host, we recommend doing a DNS override using the IP address of the host for any page that has SPDY enabled.
Please note that host override doesn't exist for HTTP/2. HTTP/2 recommends using pseudo-header fields :authority to represent host header information, but you cannot use :authority to override the host header information.
In HTTP/2 connection, the server talks to the client and checks whether it supports HTTP/2. If the client supports it, the server will redirect the client from http://www.google.com/ to https://www.google.com/, since HTTP2 only works for sites that support TLS. You may notice that in our portal, host override works for a URL such as HTTP://www.google.com. This is because the host override happens before the server communicates to the client - that's before the client is redirected to the HTTPS site that supports HTTP/2.