While culling Googlebot records from my raw log table, I'm encountering some questionable results related to the 188.8.131.52 /24 range. Here are a couple of examples.
184.108.40.206 - Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5376e Safari/8536.25 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
220.127.116.11 - Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
There are other IP's involved as well (all in the above range).
Anyway, these don't validate using the standard method (failing on the forward lookup). Here are the results.
Reverse DNS for 18.104.22.168 = crawl-66-249-70-238.googlebot.com
Domain checks out.
Forward DNS throws a socket exception: No such host is known.
The reason I'm asking about this is because I thought this was in G's range and it seems like this should validate. As I said before, I'm seeing this with everything across 22.214.171.124 /24 that claims to be Googlebot.