Background

Private IP addresses are used to conserve IP addresses from exhaustion by reserving ranges of IP addresses for the devices which reside inside a private local area network (LAN) in residential, office, and enterprise environments.

Private network addresses are not allocated to any specific individual or organization. Anyone may use these addresses without approval from regional or local Internet registries. Private IP addresses cannot be routed through the public Internet.


Private IPv4 Addresses

The Internet Assigned Numbers Authority (IANA) has reserved the following IPv4 address ranges for private networks as defined in RFC 1918:

CIDR Netmask IP Range Notations Addresses Scope Description
10.0.0.0/8 255.0.0.0 10.0.0.0 - 10.255.255.255
167772160 - 184549375
0A.00.00.00 - 0A.FF.FF.FF
16,777,214 Private Network Used for local communications within a private network. Typically this range will be broken down into smaller subnets for routing within a large enterprise network.
172.16.0.0/12 255.240.0.0 172.16.0.0 - 172.31.255.255
2886729728 - 2887778303
AC.10.00.00 - AC.1F.FF.FF
1,048,574 Private Network Used for local communications within a private network. Typically this range will be broken down into smaller subnets for routing within a large enterprise network.
192.168.0.0/16 255.255.0.0 192.168.0.0 - 192.168.255.255
3232235520 - 3232301055
C0.A8.00.00 - C0.A8.FF.FF
65,534 Private Network Used for local communications within a private network. Typically this range is used by home networks and is the default range assigned by consumer grade routers.


Carrier-Grade NAT Deployment

In April 2012, IANA allocated the block 100.64.0.0/10 for use in carrier-grade NAT scenarios.
This address block should not be used on private networks or on the public Internet.

CIDR Netmask IP Range Notations Addresses Scope Description
100.64.0.0/10 255.192.0.0 100.64.0.0 - 100.127.255.255
1681915904 - 1686110207
64.40.00.00 - 64.7F.FF.FF
4,194,302 Private Network Shared address space for communications between a service provider and its subscribers when using a carrier-grade NAT.


Link-Local Addresses

Link-local addresses are defined in RFC 6890 and RFC 3927. Their utility is in zero configuration networking when Dynamic Host Configuration Protocol (DHCP) services are not available and manual configuration by a network administrator is not desirable.

CIDR Netmask IP Range Notations Addresses Scope Description
169.254.0.0/16 255.255.0.0 169.254.0.0 - 169.254.255.255
2851995648 - 2852061183
A9.FE.00.00 - A9.FE.FF.FF
65,534 Subnet Used for link-local addresses between two hosts on a single link when no IP address is otherwise specified, such as would have normally been retrieved from a DHCP server.


Reserved IP Addresses

Similar to private IP addresses but more restrictive are reserved IP addresses. These IP addresses are designated for special usage.

CIDR Netmask IP Range Notations Addresses Scope Description
0.0.0.0/8 255.0.0.0 0.0.0.0 - 0.255.255.255
0 - 16777215
00.00.00.00 - 00.FF.FF.FF
16,777,214 Software Current network (only valid as source address).
127.0.0.0/8 255.0.0.0 127.0.0.0 – 127.255.255.255
2130706432 - 2147483647
7F.00.00.00 - 7F.FF.FF.FF
16,777,214 Host Used for loopback addresses to the local host.
192.0.0.0/24 255.255.255.0 192.0.0.0 – 192.0.0.255
3221225472 - 3221225727
C0.00.00.00 - C0.00.00.FF
254 Private Network IETF Protocol Assignments.
192.0.2.0/24 255.255.255.0 192.0.2.0 – 192.0.2.255
3221225984 - 3221226239
C0.00.02.00 - C0.00.02.FF
254 Documentation Assigned as TEST-NET-1, documentation and examples.
192.88.99.0/24 255.255.255.0 192.88.99.0 – 192.88.99.255
3227017984 - 3227018239
C0.58.63.00 - C0.58.63.FF
254 Internet Reserved. Formerly used for IPv6 to IPv4 relay (included IPv6 address block 2002::/16).
198.18.0.0/15 255.254.0.0 198.18.0.0 – 198.19.255.255
3323068416 - 3323199487
C6.12.00.00 - C6.13.FF.FF
131,070 Private Network Used for benchmark testing of inter-network communications between two separate subnets.
198.51.100.0/24 255.255.255.0 198.51.100.0 – 198.51.100.255
3325256704 - 3325256959
C6.33.64.00 - C6.33.64.FF
254 Private Network Assigned as TEST-NET-2, documentation and examples.
203.0.113.0/24 255.255.255.0 203.0.113.0 – 203.0.113.255
3405803776 - 3405804031
CB.00.71.00 - CB.00.71.FF
254 Private Network Assigned as TEST-NET-3, documentation and examples.
224.0.0.0/4 240.0.0.0 224.0.0.0 – 239.255.255.255
3758096384 - 4026531839
E0.00.00.00 - EF.FF.FF.FF
268,435,454 Internet In use for IP multicast.[12] (Former Class D network).
240.0.0.0/4 240.0.0.0 240.0.0.0 – 255.255.255.254
4026531840 - 4294967294
F0.00.00.00 - FF.FF.FF.FE
268,435,454 Internet Reserved for future use.[13] (Former Class E network).
255.255.255.255/32 240.0.0.0 255.255.255.255
4294967295
FF.FF.FF.FF
1 Subnet Reserved for the "limited broadcast" destination address.


See Also


External References





This content was last updated on February 22, 2021
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