IP addresses: Likelihood of non-reserved address falling outside of 100.*?

Question

One of the reserved IP address ranges as define here is:

Block 100.64.0.0/10

Range 100.64.0.0 – 100.127.255.255

I'm trying to construct a regex that will capture any address in this range, but I don't see a way to do it without specifying every possible value for the second 8 bits.

If I just left my regex as "any IP address beginning with 100.", would that suffice? Or to put it another way, are there any non-reserved address that beginning with 100 but which don't fall within 100.64.0.0 – 100.127.255.255?

Answer 1

To answer your question "Likelihood of non-reserved address falling outside of 100.*?": 100%

See for example http://whois.arin.net/rest/net/NET-100-0-0-0-1 and http://whois.arin.net/rest/net/NET-100-48-0-0-1. Those are just two examples of some huge ISPs using space from 100.0.0.0/8.