Table of Contents
Private vs Public IP Addresses
IP addresses are generally divided into two categories:
- Public IP Addresses
- Private IP Addresses
Understanding the difference is essential for troubleshooting network connectivity and interpreting the results of tools such as Telenegar IP Check.
Public IP Addresses
A public IP address is globally unique and can be reached over the Internet.
Public IP addresses are assigned by Internet Service Providers (ISPs) and are routable across the global Internet.
Example:
8.8.8.8 1.1.1.1 93.184.216.34
When you visit a website, the website usually sees your public IP address.
Private IP Addresses
A private IP address is used only inside a local network.
Private addresses are not routed on the public Internet.
The three private IPv4 ranges defined by RFC 1918 are:
| Range | CIDR Prefix |
|---|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 |
Examples:
192.168.1.25 10.0.0.100 172.20.15.8
Why Are Private Addresses Used?
Private addresses allow many devices to communicate within a local network without consuming globally unique public IPv4 addresses.
Typical devices using private addresses include:
- Personal computers
- Smartphones
- Printers
- Smart TVs
- IP cameras
- IoT devices
How Do Private Devices Access the Internet?
Most home and office networks use a router that performs Network Address Translation (NAT).
Example:
Laptop
192.168.1.25
│
▼
Home Router
(NAT)
│
▼
Public IP
203.0.113.25
│
▼
Internet
External websites only see the router's public IP address.
Can Two Devices Have the Same Private IP?
Yes.
Many different networks may use the same private addresses.
For example:
Home A 192.168.1.100 Home B 192.168.1.100
These devices do not conflict because they are on different private networks.
Public IP addresses, however, must be globally unique.
Which IP Address Does a Website See?
Suppose your computer has:
Private IP 192.168.1.50
Your router has:
Public IP 198.51.100.25
When visiting a website:
Website ↓ 198.51.100.25
The website does not see your private address.
IPv6
IPv6 has a similar concept.
Global addresses:
2001::/3
Unique Local Addresses (ULA):
fc00::/7
Unlike IPv4, IPv6 generally does not require NAT.
How Can I Tell Whether an Address Is Private?
Examples:
| Address | Type |
|---|---|
| 8.8.8.8 | Public |
| 1.1.1.1 | Public |
| 192.168.1.20 | Private |
| 10.0.0.15 | Private |
| 172.20.5.9 | Private |
| 203.0.113.5 | Public (documentation example) |
Private vs Public in Telenegar
Telenegar IP Check automatically determines whether an IP address is:
- Public
- Private
- Loopback
- Link-local
- Reserved
This helps users quickly identify whether an address is expected to be reachable over the Internet.
Common Misconceptions
- Private IP addresses are less secure than public IP addresses.
- False. “Private” refers to routing, not security.
- Every device connected to the Internet has its own public IPv4 address.
- False. Many devices share a single public address through NAT.
- A website can see my private IP address.
- False. It normally sees only your public IP address.
Related Topics
ip ipv4 ipv6 private-ip public-ip nat networking