Private IP address and public IP address are numerical addresses used to identify network devices. It is necessary for a network device to have a private IP address or a public IP address in order to communicate inside or outside of the network.
Private IP Address
A Private IP address is used within a local network, typically assigned by a router or other network device to each device on the network, and is only identifiable and accessible within that local network. Private IP addresses are not routed on the Internet, and therefore cannot be accessed directly from the Internet. Common private IP address ranges include:
- 10.0.0.0 to 10.255.255.255
- 172.16.0.0 to 172.31.255.255
- 192.168.0.0 to 192.168.255.255.
Usually a normal mobile phone SIM card can only get private IP addresses.
Public IP Address
A Public IP address is a globally unique address that is assigned by an Internet Service Provider (ISP) to a device and can be accessed by other internet users of the world. Usually there are two types:
- Static IP address: this IP address is fixed to a device(or server, website) and will not change.
- Dynamic IP address: since the number of public addresses is limited, public IP addresses are typically assigned dynamically and regularly by ISP, this means a device’s IP address will change periodically. When using a dynamic public IP address, Dynamic DNS service (DDNS) is an important feature to bind domain names (such as www.google.com) for devices, users do not need to search for dynamic IP addresses all the time and just remember the only one domain name to access the device.
Q: How to define whether an IP address is public IP address or private IP address?
A: The IP address within the range of 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 is really a private IP address. You can also search for IP lookup tool on the Internet to check whether this IP address is a private IP address or a public IP address.
Q: Why IP lookup tool will show my IP address a public IP address?
A: Usually IP lookup tool can only find the public IP address not able to find your device private IP address. The displayed public IP address is the network exit address you are using to access the Internet, it’s provided by ISP and used for many users at the same time.
Q: How to get a public IP address?
A: Please contact local Internet Service Provider (ISP) for this service.