According to standards set forth in Internet Engineering Task Force (IETF) document RFC-1918, the following IPv4 address ranges are reserved by the IANA for private internets, and are not publicly routable on the global internet:
- 10.0.0.0/8 IP addresses: 10.0.0.0 – 10.255.255.255
- 172.16.0.0/12 IP addresses: 172.16.0.0 – 172.31.255.255
- 192.168.0.0/16 IP addresses: 192.168.0.0 – 192.168.255.255
Note that only a portion of the “172” and the “192” address ranges are designated for private use. The remaining addresses are considered “public,” and thus are routable on the global Internet.
Use caution when setting filters to exclude these private address ranges. In some cases, Regional Internet Registries (RIRs) have issued adjacent address space to their customers and that space is in use on the global Internet.
In August 2012, ARIN began allocating “172” address space to internet service, wireless, and content providers. There have been reports from the community that many network operators are denying access to devices having IP addresses from within the entire 172 /8 range. As a result, any device with a 172.x.x.x IP address may have difficulty reaching some sites on the global Internet. The only way to solve this problem is for those operators to reconfigure their routers or firewall access controls and filter only address space from the 172.16.0.0/12 range.
FAQs
The 100.64. 0.0/10 address block is not private address space; it is shared address space. This is spelled out in RFC 6598, IANA-Reserved IPv4 Prefix for Shared Address Space (I highlighted the relevant verbiage): Introduction.
What is private IPv4 addressing? ›
Private IP addresses are commonly used for residential and corporate networks, as the addresses cannot be seen outside the private network. Internet service providers (ISPs) may also allocate a single routable IPv4 address to residential customers.
What divides the IPv4 address space 0.0 0.0 255.255 255.255 into 5 classes? ›
Classful addressing divides the IPv4 address space (0.0. 0.0-255.255. 255.255) into 5 classes: A, B, C, D, and E. However, only A, B, and C are used for network hosts.
What is the IPv4 address space? ›
The IPv4 address space is a 32 bit field. There are 4,294,967,296 unique values, considered in this context as a sequence of 256 "/8s", where each "/8" corresponds to 16,777,216 unique address values.
Is 100.64 a private network? ›
In April 2012, IANA allocated the 100.64.0.0/10 block of IPv4 addresses specifically for use in carrier-grade NAT scenarios. This address block should not be used on private networks or on the public Internet.
What is the 255.255 255.0 address space? ›
A subnet mask of 255.255. 255.0 means that the device can connect with any other device on the network with an IP address containing identical values in the first three octets. 255 means that the value of that octet must be identical. 0 means that the value can be anything.
What does a private IPv4 address look like? ›
The way to tell is to reference a standard used by TCP/IP: An IPv4 address beginning with any of the following is a private address: 10. 172.16., 172.17., 172.18, etc up to 172.30.
Should I keep my IPv4 address private? ›
Using the IP address, computers can receive information. However, IP addresses can also be used to track the user's approximate location and web activity, so hiding is a must if you want to remain private online.
How do I check my private IP address? ›
Find your IP address in Windows
- Select Start > Settings > Network & internet > Wi-Fi and then select the Wi-Fi network you're connected to.
- Under Properties, look for your IP address listed next to IPv4 address.
What does 0.0 0.0 255.255 255.255 mean? ›
0.0. 0.0 – Represents the “default” network, i.e. any connection. 255.255. 255.255 – Represents the broadcast address, or place to route messages to be sent to every device within a network.
IP (version 4) addresses are 32-bit integers that can be expressed in hexadecimal notation. The more common format, known as dotted quad or dotted decimal, is x.x.x.x, where each x can be any value between 0 and 255. For example, 192.0. 2.146 is a valid IPv4 address.
How many bits are there in an IPv4 address? ›
IPv4 addresses are 32-bit numbers that are typically displayed in dotted decimal notation. A 32-bit address contains two primary parts: the network prefix and the host number. All hosts within a single network share the same network address.
What does an IPv4 address tell you? ›
An IPv4 address is a 32-bit address that identifies a device on a network. It is made of 4 groups of numbers (octets) with up to 3 numbers each. The IPv4 will identify the network and the individual host on the network.
How to check IPv4 address? ›
First, click on your Start Menu and type cmd in the search box and press enter. A black and white window will open where you will type ipconfig /all and press enter. There is a space between the command ipconfig and the switch of /all. Your IP address will be the IPv4 address.
How to change IPv4 address? ›
How to change your IP address on Windows 10
- Click Start > Settings > Network & Internet.
- Under your local area connection, click Properties.
- Under IP assignment, click Edit.
- Choose Manual, toggle on IPv4, and enter the IP address. Then click Save.
How do you calculate address space? ›
Given a subnet mask, here's how to figure out address space size:
- Convert subnet mask to binary.
- Count number of zeros.
- Raise 2 to this power, This number gives you the available addresses.
- The first address in an address space is the network address and cannot be used as a host address.
What is the address space of 10.0 0.0 8? ›
A network numbered “10.0. 0.0/8” (which is one of those reserved for private use) is a network with eight bits of network prefix, denoted by “/8” after the oblique. The “8” denotes that there are 24 bits left over in the network to contain IPv4 host addresses: 16,777,216 addresses to be exact.
What is 169.254 address space? ›
169.254 is a private IP (Internet Protocol) address that the device automatically assigns itself when it can't get a valid IP from the router's DHCP (Dynamic Host Configuration Protocol) server. Essentially, getting any IP that begins with 169.254 tells you that something isn't working.
What is the address range for 172.16 0.0 12? ›
Private IP Numbers
Prefix | First Address | Last Address |
---|
10.0.0.0/8 | 10.0.0.0 | 10.255.255.255 |
172.16.0.0/12 | 172.16.0.0 | 172.31.255.255 |
192.168.0.0/16 | 192.168.0.0 | 192.168.255.255 |