Mediapartners-Google + nginx = 499 code. Check your logs

Question

Google

Mediapartners-Google is a Google robot user agent that collects website content for subsequent display of contextual advertising.

How it works. The visitor has landed on the page. Loaded java script from google site. The Google server looked at the referer and sent a Mediapartners-Google robot there.

The essence of the problem:

Mediapartners-Google requests the page twice and with exactly the same HTTP headers. Only for the first time, it immediately sends the [FIN, ACK] flags, that is, it breaks the connection without waiting for a response. What remains the eloquent error 499 in the web server logs. A second later, it makes a second request and already takes the entire document.

It surprises me that mentions of this situation are quite rare on the Internet, although if the jamb is on the side of Google, then there should be a lot of discussions.

1) I want to hear thoughts on the topic of what it could be.
2) Who spins adsense ads and who has a server on nginx, grep the logs. Do you see something similar or not?

Answer 1

I checked it on one site - in the access log I found such a
66.249.71.75 - - [13/Apr/2011:14:26:39 +0300] "GET [...] HTTP/1.1" 499 0 "-" "Mediapartners-Google"