I received the following in my log:
[Mon Oct 05 11:04:35 2015] [error] [client 66.249.75.xxx] File does not exist: /path/to/user/public_html/apple-app-site-association
xxx in the log is a number between 11 and 245. Also, the source IP is 66.249.69.yyy where yyy is 7, 59, and 94.
Based on the entry, it appears google is trying to look up http://www.example.com/apple-app-site-association where www.example.com is every domain name that the server manages including the server IP address itself.
Why would google randomly search for apple-app-site-association?