Welcome to WebmasterWorld Guest from 18.104.22.168
Some -- but not all -- are pages I block with robots.txt and removed using Webmaster Tools. (They weren't always blocked.)
I've found at least one non-blocked article that's indexed under the IP address but NOT the URL.
On the (potential) plus side, Webmaster Tools is showing some of these as sources of "external links" to pages on my site.
Additional weirdness: I just noticed that G is indexing both what Ping shows as my site's IP address AND a number one digit lower. I.e., if my address is 99.99.999.99, what's in the index is 99.99.999.98. I use a VPS, if that tells you anything. Both have about 500 pages.
Should I be concerned? What should I do?
These will help you correct the issue with the ip being indexed but it needs to be fixed and fixed fast.
What's curious is that it wasn't a competitor -- it was a post I had written on a 3rd party forum, according to a G search for "link:99.99.999.98" . The post I wrote used the URL form, but somehow Google indexed it as the IP address.
Stranger still, G indexed all three: ..98, ..99 AND www.example.com from the same post. .98 is the IP of my DEV site, .99 is www.
Anyway, both IP addresses now 301 to www.example.com. THANKS!