IANA supplies criteria on this issue. For IPv4, here is what they've inside their "Distinctive function deal with registry". Meaning, for our purposes, something in these tackle blocks shouldn't be assigned simply because they shouldn't be routable "publicly". Stack Exchange community is made of 183 Q&A communities including Stack Overflow, https://60-loan37148.ourcodeblog.com/36921027/the-fact-about-255-payday-loan-that-no-one-is-suggesting