172 IP Addresses: What You Need to Know
Learn how 172 IP address ranges are used on private networks, how they differ from other RFC 1918 ranges, and where you are likely to see them.
The 172 IP Address Ranges Explained
When people talk about “172 IP addresses,” they are usually referring to the private address range 172.16.0.0 through 172.31.255.255. This block is reserved by RFC 1918 for use on internal networks and is not routable on the public internet. Home routers, corporate LANs, and cloud VNets often assign addresses from this private 172 range to devices behind a gateway.
Outside of that private range, other 172.x.x.x addresses are globally routable public IP addresses that can be assigned to internet-facing hosts. It is important to distinguish between the specific private block 172.16.0.0/12 and the rest of the 172.0.0.0/8 space, which follows normal public addressing rules.
172 Addresses vs. Other Private Ranges
The private 172.16.0.0/12 space is one of three major private IPv4 ranges, alongside 10.0.0.0/8 and 192.168.0.0/16. All three are reserved for internal use and are widely used in homes, businesses, and cloud environments. In practice, 192.168.x.x addresses are common in consumer routers, while 10.x.x.x and 172.16.x.x ranges appear more often in corporate or cloud networks.
Choosing between these ranges is mostly a design decision. Administrators consider overlap with existing networks, VPNs, and partners, as well as convenience for subnetting. Regardless of which private range you use, traffic must pass through a router performing network address translation (NAT) before it can reach the public internet.
Working with 172 Addresses on Your Network
If your device shows an address in the 172.16.0.0–172.31.255.255 range, it is part of a private network. You will typically access the internet through a gateway or router with its own public IP address. Tools like ipconfig, ifconfig, or your router’s status page can show both the private 172 address and the external address visible to websites.
When designing networks, document which parts of the 172.16.0.0/12 range you use for different sites or segments, and avoid reusing the same blocks across independent environments that must later be connected. Consistent planning makes VPNs, cloud connectivity, and troubleshooting much easier.