Work out reserved ip range checker instantly with clear inputs, formula shown and shareable results.
IANA maintains a special-purpose address registry covering roughly 15 IPv4 blocks that are not ordinary global unicast space. Some, like RFC 1918 ranges, are perfectly usable inside your own network; others such as 0.0.0.0/8, 127.0.0.0/8, 169.254.0.0/16, the documentation TEST-NETs and class E must never appear on an interface.
Special-purpose lookup
for each registry block: match if (address AND mask(prefix)) equals the block network; report the RFC and whether hosts may use it
It is reserved for documentation. Real traffic to it may be dropped or reused elsewhere, and copying examples verbatim into production causes confusing failures.
Both. They are reserved from the global routing table but explicitly intended for use inside private networks behind NAT.