IANA supplies specifications on this issue. For IPv4, here is what they may have of their "special intent deal with registry". Meaning, for our purposes, just about anything in these deal with blocks shouldn't be assigned given that they should not be routable "publicly". A subnet mask refers back to https://shulamithh890zza2.blogunteer.com/35601481/the-definitive-guide-to-255-payday-loan