I cannot figure out why my rankings dropped, at the same time I deployed 4 Nginx cache servers on different continents.
When I serve the PHP pages, I set this expiration header from the origin server, so my Nginx could cache these pages for x amount of time without asking for them at the origin server again, and to serve them faster to nearby clients.
Are these bad for SEO maybe? Do they also signal to Googlebot that these pages will expire in this amount of time and Google might stop sending traffic to them until it finds them again?
Do I normally need to trim these headers on the last servers and only use these headers between my Nginx cache and the origin server?
$cache_seconds = 60*5; header("Expires: ".gmdate('D, d M Y H:i:s \G\M\T', time()+$cache_seconds)); header("Cache-Control:public, max-age=".$cache_seconds);