You know; Google suggest us to use Vary Tag at our diynamic content mobile pages.

please check the link: https://developers.google.com/webmasters/mobile-sites/mobile-seo/configurations/dynamic-serving

I couldnt understand how to use this tag. Do you have any idea where will i put it?

and how will we calculate Content-Length?

and how to customize this part 'GET /page-1 HTTP/1.1'?

is this a meta-tag(<>)? or just copy paste these lines to all our mobile pages?

HTTP/1.1 200 OK
Content-Type: text/html
Vary: User-Agent
Content-Length: 5710

Could you give an example of usage this Vary Code; in example.php for example.. where wil i put it; before tag; instead of tag?

<html> HTTP/1.1 200 OK Content-Type: text/html Vary: User-Agent Content-Length: 5710 <body> </body> </html> etc..

  • This is server response header stuff and not HTML stuff. The page you linked to was terrible. Here are some links: searchengineland.com/… stackoverflow.com/questions/1975416/… and w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.44 There is little out there on this. Essentially, (if I read things right) the vary tag (not HTML) is for sites that are mobile only and is a setting within the web server itself.
    – closetnoc
    Commented Jan 15, 2015 at 0:34
  • is that mean, i dont need to do anyting? (if its auto creating by server.. my site has diynamic content mobile version )
    – deniz
    Commented Jan 15, 2015 at 0:52
  • I don't know if you do or not. It depends upon your environment. If you are using responsive design, then "No." You do not have to make this change. If you have a mobile site, then it is an option to study whether you make a change to your mobile site configuration or not. It appears to be primarily for caching. If you are worried about whether or not to make this change, I would say do not worry about it today but study it. It is a technical study that will take time to understand. Perhaps someone will have a good answer for you.
    – closetnoc
    Commented Jan 15, 2015 at 0:57
  • thank you so much closetnoc.. i'm going to wait; as you said too 'its not a urgent problem' (my site is changing its view by php; i mean, its neither responsive nor mobile site; it calls dynamic content)
    – deniz
    Commented Jan 15, 2015 at 1:36

1 Answer 1


What you're looking for is setting a header value for Vary.

The following PHP example will add a header value for:

Vary: Mozilla/1.22 (compatible; MSIE 5.01; PalmOS 3.0) EudoraWeb 2

$httpRequest->setHeaders(array('Vary' => 'Mozilla/1.22 (compatible; MSIE 5.01; PalmOS 3.0) EudoraWeb 2'));

You will want to use PHP's $_SERVER['HTTP_USER_AGENT']; to detect the user-agent.

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