Caught a dozen HEAD requests for image files from the UA: ICAP-IOD
No robots.txt request. All these files are noindexed via X-Robots-Tag (of course the file header would need to be read for the tag to be found.)
ICAP-IOD making requests from Internap:
216.223.24.0 - 216.223.27.255
216.223.24.0/22
Regardless of intent, I blocked them via UA and IP range.
Other Internap ranges I have blocked are:
63.251.0.0 - 63.251.255.255
63.251.0.0/16
66.150.0.0 - 66.151.255.255
66.150.0.0/15
69.25.0.0 - 69.25.255.255
69.25.0.0/16
70.42.0.0 - 70.42.255.255
70.42.0.0/16
74.217.0.0 - 74.217.255.255
74.217.0.0/16
95.172.68.0 - 95.172.71.255
95.172.68.0/22
208.64.56.0 - 208.64.63.255
208.64.56.0/21
216.52.0.0 - 216.52.255.255
216.52.0.0/16