Looking through the logs of my company website server I see a new user-agent from google IP-space - Adsbot. I ran a back-check and it turns out it first hit my site on Sept 19, 21, Oct 2, 10 and 15. No previous hits ever from that bot. Also interesting, only the Oct 10 hit was to our default.html page. The other 4 hits were to pdf files (these are reprints of scientific papers).

I've tried looking for some info as to what the adbot's function is- something about assessing the suitability of our site to either host advertising - or be the source of ad content? Our site was designed 17 years ago and has not changed (in terms of structure / layout) and has no internal links or references to google-anything. The google search bot hits our site each and every day, usually pulls off 50 to 100 pages/files each day, and it's been doing this for years. This is the first time I'm seeing the Adsbot. I don't know if this is related, but I guess it was earlier this year that I started to see google request the file ads.txt from our site - which we don't have.