There's no reason why you can't assign 3.0.0.0 to a host, it'll work fine. Just make sure you don't put anything else there by convention. 3.255.255.255 would

There's no reason why you can't assign 3.0.0.0 to a host, it'll work fine. Just make sure you don't put anything else there by convention. 3.255.255.255 would be the default broadcast address, but not only can you use a different address (in fact, any address you want for broadcast, you just need to configure it), but this is also not a real /8... it's 3.0.0.0/15 according to ARIN. https://whois.arin.net/rest/net/NET-3-0-0-0-2/pft?s=3.0.0.0 https://whois.arin.net/rest/net/NET-3-0-0-0-2/pft?s=3.0.0.0 3.255.255.255 is default broadcast for 3.128.0.0/9.