Hey just wanted to mention that it does appear as though 100.0.0.0/12 does get routed by a number of internet hosts:

traceroute -n 100.1.1.1
 1  192.168.2.1  16.953 ms  18.672 ms  26.622 ms
 2  192.168.1.1  63.993 ms  66.595 ms  67.210 ms
 3  50.185.26.1  81.620 ms  84.669 ms  87.114 ms
 4  68.87.196.89  91.254 ms  91.479 ms  92.388 ms
 5  68.87.57.221  87.381 ms 68.87.55.229  104.986 ms 68.87.55.225  106.784 ms
 6  68.85.155.234  109.069 ms 68.85.155.238  91.181 ms 68.85.155.234  102.066 ms
 7  * * *
 8  68.86.86.102  106.262 ms  106.159 ms  106.481 ms
 9  68.86.82.94  100.819 ms  104.484 ms  101.623 ms
10  23.30.206.94  139.012 ms  138.273 ms  158.165 ms
11  130.81.209.171  193.143 ms * *
12  * * *
13  100.1.1.1  159.241 ms  155.888 ms  156.733 ms

or

traceroute 100.1.1.1
traceroute to 100.1.1.1 (100.1.1.1), 30 hops max, 60 byte packets
 1  192.168.2.1 (192.168.2.1)  41.102 ms  41.890 ms  44.911 ms
 2  192.168.1.1 (192.168.1.1)  50.067 ms  50.663 ms  51.156 ms
 3  50.185.26.1 (50.185.26.1)  60.095 ms  61.839 ms  87.606 ms
 4  GE-2-37-ur01.fremontcev2.ca.sfba.comcast.net (68.87.196.89)  103.734 ms  104.030 ms  177.000 ms
 5  te-0-7-0-21-sur03.oakland.ca.sfba.comcast.net (68.87.57.221)  176.024 ms te-0-7-0-19-sur03.oakland.ca.sfba.comcast.net (68.85.57.141)  176.480 ms te-0-7-0-21-sur03.oakland.ca.sfba.comcast.net (68.87.57.221)  176.684 ms
 6  te-0-2-0-5-ar01.sfsutro.ca.sfba.comcast.net (69.139.199.78)  178.344 ms te-0-2-0-0-ar01.sfsutro.ca.sfba.comcast.net (68.85.155.234)  19.639 ms te-0-2-0-7-ar01.sfsutro.ca.sfba.comcast.net (68.87.194.50)  41.532 ms
 7  * * *
 8  he-2-9-0-0-cr01.losangeles.ca.ibone.comcast.net (68.86.86.102)  59.336 ms  98.858 ms  98.859 ms
 9  be-13-pe02.11greatoaks.ca.ibone.comcast.net (68.86.82.94)  98.056 ms  102.286 ms  99.433 ms
10  23.30.206.94 (23.30.206.94)  273.404 ms  274.855 ms  276.308 ms
11  B200.NWRKNJ-LCR-22.verizon-gni.net (130.81.209.171)  301.458 ms P0-15-0-0.NWRKNJ-LCR-22.verizon-gni.net (130.81.199.17)  301.773 ms  302.699 ms
12  * * *
13  L101.NWRKNJ-VFTTP-142.verizon-gni.net (100.1.1.1)  378.294 ms  379.111 ms  378.479 ms

I think we agreed that this is okay as it's supposed to be strictly for internal NAT only, and so any public routing is sort of incidental. Just wanted folks to be apprised of the situation.