Varnish不会缓存多个wordpress

I have setup Varnish on a high end dedicated server with WHM which is running around 10-13 websites, all on WordPress. I'm seeing that hit rate is really very low and miss rate is very high in "varnishhist". Also, when I do varnishtop -i txurl, I just see "/" URL (and not each website URL) being requested from Apache at really very higher rate. Below is an excerpt:

4.02 TxURL /
1.00 TxURL /wp-content/uploads/2014/12/034kj343.jpg
0.96 TxURL /wp-content/uploads/2014/12/dfkkj30434.jpg
0.96 TxURL /wp-content/uploads/2014/10/3403402022.jpg

I believe that varnish must even cache the home page of every single site and send back to client rather than requesting from backend. Any suggestions please?

OK. I managed to find the solution. Here is my current VCL file which works very good.

 sub vcl_recv{   
    if (req.http.Cookie && req.http.Cookie ~ "(wordpress_|PHPSESSID)")
    { return(pass); }

    if (req.url ~ "wp-admin|wp-login") {
    return (pass);
    }
    else{
    unset req.http.Cookie;
    } #since we can not unset all, but leave wp-admin
}
sub vcl_backend_response {
    if (bereq.url !~ "wp-admin|wp-login") {
            unset beresp.http.Set-Cookie;
    }
    #beware that you are ignoreing all the headers now:
    unset beresp.http.Cache-Control;

    # cache everything for 60 minutes
    if(beresp.ttl <= 0s) { set beresp.ttl = 3600s; }
}