Google.com and clients1.google.com/generate_204

I found this old Thread while google'ing for generate_204 as Android seems to use this to determine if the wlan is open (response 204 is received) closed (no response at all) or blocked (redirect to captive portal is present). In that case a notification is shown that a log-in to WiFi is required...

Like Snukker said, clients1.google.com is where the search suggestions come from. My guess is that they make a request to force clients1.google.com into your DNS cache before you need it, so you will have less latency on the first "real" request.

Google Chrome already does that for any links on a page, and (I think) when you type an address in the location bar. This seems like a way to get all browsers to do the same thing.