Reserved IP Address Ranges
The address blocks that are not ordinary public addresses, from IANA's special-purpose registries, and a checker that tells you which one an address belongs to.
100.64.12.7 is in 100.64.0.0/10: Shared address space (CGNAT).
IPv4 special-purpose blocks
| Block | Purpose | Defined in | Reachable on the internet |
|---|---|---|---|
| 0.0.0.0/8 | UnspecifiedThis network | RFC 791 | No |
| 10.0.0.0/8 | Private networkPrivate-Use | RFC 1918 | No |
| 100.64.0.0/10 | Shared address space (CGNAT)Shared Address Space (CGNAT) | RFC 6598 | No |
| 127.0.0.0/8 | LoopbackLoopback | RFC 1122 | No |
| 169.254.0.0/16 | Link-localLink-Local | RFC 3927 | No |
| 172.16.0.0/12 | Private networkPrivate-Use | RFC 1918 | No |
| 192.0.0.0/24 | Protocol assignmentIETF Protocol Assignments | RFC 6890 | No |
| 192.0.2.0/24 | DocumentationDocumentation (TEST-NET-1) | RFC 5737 | No |
| 192.31.196.0/24 | AnycastAS112-v4 | RFC 7535 | Yes |
| 192.52.193.0/24 | Protocol assignmentAMT | RFC 7450 | Yes |
| 192.88.99.0/24 | ReservedDeprecated 6to4 Relay Anycast | RFC 7526 | No |
| 192.168.0.0/16 | Private networkPrivate-Use | RFC 1918 | No |
| 192.175.48.0/24 | AnycastDirect Delegation AS112 Service | RFC 7534 | Yes |
| 198.18.0.0/15 | BenchmarkingBenchmarking | RFC 2544 | No |
| 198.51.100.0/24 | DocumentationDocumentation (TEST-NET-2) | RFC 5737 | No |
| 203.0.113.0/24 | DocumentationDocumentation (TEST-NET-3) | RFC 5737 | No |
| 224.0.0.0/4 | MulticastMulticast | RFC 5771 | No |
| 240.0.0.0/4 | ReservedReserved for future use | RFC 1112 | No |
| 255.255.255.255/32 | BroadcastLimited Broadcast | RFC 919 | No |
IPv6 special-purpose blocks
| Block | Purpose | Defined in | Reachable on the internet |
|---|---|---|---|
| ::/128 | UnspecifiedUnspecified Address | RFC 4291 | No |
| ::1/128 | LoopbackLoopback Address | RFC 4291 | No |
| ::ffff:0:0/96 | TranslationIPv4-mapped Address | RFC 4291 | No |
| 64:ff9b::/96 | TranslationIPv4-IPv6 Translation (NAT64) | RFC 6052 | Yes |
| 64:ff9b:1::/48 | TranslationLocal-use IPv4/IPv6 Translation | RFC 8215 | No |
| 100::/64 | ReservedDiscard-Only Address Block | RFC 6666 | No |
| 2001::/32 | TranslationTEREDO | RFC 4380 | No |
| 2001:2::/48 | BenchmarkingBenchmarking | RFC 5180 | No |
| 2001:db8::/32 | DocumentationDocumentation | RFC 3849 | No |
| 2001:10::/28 | ReservedDeprecated (ORCHID) | RFC 4843 | No |
| 2001:20::/28 | Protocol assignmentORCHIDv2 | RFC 7343 | Yes |
| 2002::/16 | Translation6to4 | RFC 3056 | No |
| 3fff::/20 | DocumentationDocumentation | RFC 9637 | No |
| 5f00::/16 | Protocol assignmentSegment Routing (SRv6) SIDs | RFC 9602 | No |
| fc00::/7 | Unique local (ULA)Unique-Local | RFC 4193 | No |
| fe80::/10 | Link-localLink-Local Unicast | RFC 4291 | No |
| ff00::/8 | MulticastMulticast | RFC 4291 | No |
Taken from the IANA IPv4 and IPv6 Special-Purpose Address Registries, plus multicast and the old class E range. “Reachable on the internet” follows IANA's “globally reachable” column. A private address is never routed on the public internet.
Not every IP address is meant to be routed on the internet. IANA keeps two special-purpose address registries, one for IPv4 and one for IPv6, listing the blocks set aside for private networks, loopback, link-local use, documentation, benchmarking, protocol translation and other purposes. Together with the multicast ranges and IPv4’s old class E, they are the addresses a router should never accept as ordinary public destinations, often called bogons.
The ones you are most likely to meet: the three private ranges of RFC 1918 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) used in almost every home and office network; shared address space 100.64.0.0/10 used by providers for carrier-grade NAT; link-local 169.254.0.0/16 and fe80::/10, which a device gives itself when nothing else configures it; and the documentation blocks (192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, 2001:db8::/32) reserved for examples like the ones on this site.
The table is generated from the same registry data this site uses to classify every lookup, and the checker tells you which block an address belongs to, right in your browser.
Frequently asked questions
My router's WAN address starts with 100.64. Is that a problem?
It means your provider uses carrier-grade NAT: you share a public IPv4 address with other customers. Browsing works normally, but you cannot open ports to the internet over IPv4. IPv6 or a fixed public address solves it.
Why did my PC get a 169.254.x.x address?
It asked for an address (DHCP) and got no answer, so it assigned itself a link-local address. Check the cable or Wi-Fi connection and the router's DHCP server.
Can I use 192.0.2.0/24 or 2001:db8::/32 in my network?
You should not. They are reserved for documentation, so examples never collide with real networks. Use the private ranges, or unique local addresses (fd00::/8) for IPv6.