Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

Paul_Z's avatar
Paul_Z
Icon for Altocumulus rankAltocumulus
Jan 02, 2026

Any way to cache HEAD request

Hi, I was wandering if anybody had any ideas on how to cache a HEAD request on an f5? Running multiple web sites, HEAD method requests are the worst, as the f5 refuses to cache and the back end serve...
application delivery
Paul_Z's avatar
Paul_Z
Icon for Altocumulus rankAltocumulus
Jan 05, 2026

I'm not sending any significant header data. A HTTP HEAD method request is sent to see if the page has changed & typically has content length & a few other headers, but for just the headers to be returned - the servers have to go through the normal GET method. So the only saving in the whole process is the network traffic of the body not being returned to the requestor. That is why it would be beneficial for the f5 to cache it just like a GET method. 

  • Paulius's avatar
    Paulius
    Icon for MVP rankMVP
    Jan 06, 2026

    This might work for your purpose but I haven't tested it before so you might consider doing it in a lab or dev environment.

    when HTTP_REQUEST {
    # Check if the request method is HEAD
    if { [HTTP::method] eq "HEAD" } {
        # Check if we have a cached response for this request
        if { [cache lookup -key [HTTP::uri]] ne "" } {
            # Serve the cached response
            HTTP::respond 200 content [cache lookup -key [HTTP::uri]]
        } else {
            # Cache the response for future HEAD requests (optional)
            # Continue processing the request and cache the response if applicable
            cache add -key [HTTP::uri] -value [HTTP::response]
            # Proceed with the original request
            forward
        }
    } else {
        # If the method is not HEAD, forward the request normally
        forward
    }
}