172 IP Addresses: What You Need to Know

IP addresses, both public and private, are essential for communication across the Internet. One range of IPs commonly used by network administrators is the 172 IP address range. As a class B IP address range, it allows for a large number of devices to connect to the same network. In this article, explore what 172 IP addresses are, how they're used, and how they can benefit your network.

What is a 172 IP address?

172 IP addresses are a range of unique numerical codes assigned to devices connected to a network. These addresses allow devices to communicate and exchange data with each other.

IP addresses have 16 bits. Those with bits in the first octet that start with 172 can be public or private; it depends on their second octet. If the second octet of an 172 IPv4 address is between 16 and 31, you have a private IP address. Therefore, these addresses remain reserved for private use and users cannot directly access them from the Internet.

However, IPs outside of that range - like 172.15.x.x or 172.32.x.x - are considered public. This is because they're not part of the designated private IP address range. They are routable on the global Internet. However, 172.16 and 172.31 addresses are still in the private range.

The use of private 172 IP addresses helps conserve the limited supply of publicly routable IP addresses assigned by the Internet Assigned Numbers Authority (IANA). By using them, organizations can connect multiple devices to the Internet using a single public IP address, reducing the need for additional public IP addresses.

What class network is a 172 address?

172 IP addresses belong to class B of IP addresses. They range from 128.0.0.0 to 191.255.255.255. Because 172 addresses fall between the first octet range of 128 and 191, they are class B as opposed to class C or class A.

Class B allows for a large number of available IP addresses, as it has a total of 1,048,576 IPs available. Medium- to large-sized networks use these IPs, as they require a large number of IP addresses. The addresses provide up to 16,384 networks and up to 65,534 hosts per network.

Uses of 172 IPs

Every IP address is a unique numerical identifier assigned to a device on a network. Its primary purpose is to locate devices on a network and enable communication between them.

When a device sends a message or a data packet over the network, it includes its own IP address as well as the IP address of the intended recipient. This enables the data to travel to the correct device on the network.

Private networks, such as those found in homes, small businesses, and offices, commonly use 172 IP addresses. Local area networks (LANs) use them to identify devices on those networks.

On a private network, many devices - from computers to printers to servers 0 - receive IPs from the 172 IP range. These addresses establish connections between devices within the network, allowing them to effectively share information and resources.

Users can't access private 172 IPs from the Internet, meaning that any device outside the private network can't access devices within the network using that private IP. To access devices within the network from the Internet, the network must use a public IP.

What's the range of 172 IP private addresses?

The 172 IP address range goes from 172.16.0.0 to 172.31.255.255. The range provides over a million IP addresses, which is more than enough for larger local networks. These IPs identify devices within the network, enabling them to communicate with each other.

Keep in mind that private IP addresses can't access the Internet directly. To communicate with devices on the Internet, the IPs must translate to a public IP address through a device like a network address translator (NAT).

Advantages of using 172 addresses

The 172 IP address range is widely used in private networks due to its many benefits, including:

It enables communication between devices. One of the primary benefits of using 172 IP addresses is ample address space. The range provides over a million unique addresses, meaning organizations can easily accommodate multiple devices and users without worrying about running out of IP addresses.
It's easy to manage. Since 172 IP addresses are part of the private IP address range, they can be easily managed within the network without the need for public IP addresses. This simplifies network administration and reduces the likelihood of configuration errors.
It provides enhanced security. 172 IPs enhance network security since they aren't accessible from the Internet. Therefore, devices within the network are better protected against external threats.

Disadvantages of using 172 addresses

Though the 172 IP address range has many benefits, it also has some disadvantages worth noting.

It's not globally unique. Although 172 IPs can be private, they aren't unique. This means that multiple organizations can use the same private IP ranges without conflict. However, it can also create issues when two or more organizations with the same IP range need to communicate.
It's not routable on the public Internet. You can't directly access devices with 172 IP addresses from the Internet without additional configuration, like network address translation (NAT) or a virtual private network (VPN). Therefore, this creates limitations for organizations that need remote access to internal networks.
There are troubleshooting issues. Because private IPs aren't unique, it can be difficult to identify and troubleshoot issues that occur across multiple networks.

How many IP addresses are in 172?

Because the industry retired the old classful addressing system, the classless inter-domain routing (CIDR) system replaced it. This results in several classes of IP addresses. For the 172 range, however, there are 16,777,214 IP addresses available. The range can be divided into smaller subnets to accomodate different departments within an organization, but this is the total number.

Note that not all of the IPs in that range are available for use. The IANA reserves some IPs for special purposes, like multicast addresses or loopback addresses. However, the vast majority of the IP addresses in this range are available for use in private networks.

What's the difference between 172 and 192 IP addresses?

The primary difference between the 192 and 172 addresses is the class of address that they belong to.

The IP address range of 172.x.x.x is a class B address range. The first two octets dictate the network portion of the address; the remaining two are for the host portion. This provides up to 65,534 host addresses per network.

On the other hand, the 192 IP address range is a class C address range. The first three octets are the network portion and only the fourth octet is available for host addresses. This, then, provides up to 254 host addresses per network.

Frequently asked questions

Is 172.16.0.1 private or public?

It is a private IP address. Private IP addresses aren't visible on the Internet, but they allow you to connect to devices in your LAN.

Is 172.32 a private IP?

No, 172.32 is a public IP address because it's outside the designated Class B private range. The private portion of the 172 address range only goes from 172.16 to 172.31. Therefore, addresses outside this range are available as public addresses.

Is 172.17 a private IP?

Yes, 172.17 is a private address space reserved for private use.

Is 172.1.1.1 a private IP address?

No, 172.1.1.1 is a public IP address on the Internet. The IP address falls within the 172.0.0.0/8 range, which is a public range.

Keep in mind that just because an IP isn't private doesn't necessarily mean that it's accessible from the public Internet. The accessibility of an IP depends on the network configuration and firewall settings of the network it belongs to.

What is the Class B private 172 IP range?

The class B private range goes from 172.16.0.0 to 172.31.255.255.