pingAn IP address is a unique number given to every device on a network.
IP = Internet Protocol.
It helps devices:
๐ It works at the Network Layer
Simple meaning:
Device A <--> Internet <--> Device B
(IP: A) (IP: B)
There are two versions:
You want to send a letter to a friend.
No house address = the post office cannot deliver it.
Every phone, laptop and website needs an address too. That address is called an IP address.
Your friend's house = Your device
House address = IP address
Post office = The internet (routers)
Letter = Your data
Data on the internet travels in small pieces called packets.
Each packet needs two things:
The IP address is that "from" and "to" label.
Your laptop Website server
192.168.1.10 ---> [Router] ---> Internet ---> 93.184.216.34
(from) (to)
No address, no delivery. Simple.
Four numbers, separated by dots. Each number is between 0 and 255.
192.168.1.10
Why 0 to 255? Each number is stored in 8 bits. Four numbers x 8 bits = 32 bits in total.
Total possible addresses: 2^32 = 4,294,967,296 (about 4.3 billion).
โ ๏ธ The world has more devices than that. Phones, laptops, TVs, cameras, servers... we ran out.
IPv6 was created to solve the shortage.
It uses numbers and letters (hexadecimal, meaning digits 0-9 plus letters a-f), separated by colons.
2001:db8::1
The :: is a shortcut for a long run of zeros.
Short form : 2001:db8::1
Full form : 2001:0db8:0000:0000:0000:0000:0000:0001
IPv6 uses 128 bits. Total addresses: 2^128, about 3.4 x 10^38.
That is so many, we will not run out.
| IPv4 | IPv6 | |
|---|---|---|
| Looks like | 192.168.1.10 |
2001:db8::1 |
| Size | 32 bits | 128 bits |
| Written in | Decimal numbers | Hexadecimal |
| Separator | Dot . |
Colon : |
| Total addresses | About 4.3 billion | About 3.4 x 10^38 |
| Status | Still the most used | Growing every year |
Both run side by side today. Most devices have an IPv4 and an IPv6 address at the same time.
Not every address is visible on the internet.
Public IP Your address on the internet. Your ISP (internet provider) gives it to you. Websites see this one.
Private IP Your device's address inside your home network. Only devices in your home can use it.
These ranges are always private (IPv4):
| Range | Common use |
|---|---|
10.0.0.0 to 10.255.255.255 |
Big networks, offices |
172.16.0.0 to 172.31.255.255 |
Mid-size networks |
192.168.0.0 to 192.168.255.255 |
Home Wi-Fi routers |
Two special addresses to remember:
| Address | Meaning |
|---|---|
127.0.0.1 (IPv6: ::1) |
localhost: your own device talking to itself |
169.254.x.x |
Self-assigned. Something went wrong (see errors below) |
Your home has many devices. Your ISP gives you only one public IP.
Your router handles this. The trick is called NAT (Network Address Translation).
Think of an office reception desk. One phone number for the company, and reception forwards each call to the right desk.
Phone 192.168.1.10 --\
Laptop 192.168.1.11 ---+--> [ ROUTER ] --> Internet
Smart TV 192.168.1.12 --/ one public IP
(example: 203.0.113.5)
Websites see only the router's public IP.
They never see your private 192.168.x.x.
๐ก Your public IP can change. Most home ISPs give a dynamic IP, which may change when your router restarts.
Open Command Prompt and run:
ipconfig
Look under your active adapter (Wi-Fi or Ethernet).
Sample output (yours will differ):
Wireless LAN adapter Wi-Fi:
IPv6 Address. . . . : 2001:db8::1a2b
IPv4 Address. . . . : 192.168.1.10
Open Terminal and run:
ip addr
Look for the inet line (IPv4) and the inet6 line (IPv6).
Sample output (yours will differ):
2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP>
inet 192.168.1.10/24 brd 192.168.1.255 scope global wlan0
inet6 2001:db8::1a2b/64 scope global
Ignore lo (that is localhost, 127.0.0.1).
curl ifconfig.me
This shows the address websites see, not the one from ipconfig.
ping sends a tiny message to an address and waits for a reply.
If replies come back, the path works.
Windows (stops by itself after 4 replies):
ping 8.8.8.8
Linux (never stops on its own, so limit it):
ping -c 4 8.8.8.8
Or press Ctrl + C to stop it.
8.8.8.8 is Google's public DNS server. It is a safe address to test with.
| Error / Symptom | Cause | Fix |
|---|---|---|
IP starts with 169.254 |
Device asked the router for an address and got no answer (self-assigned) | Restart the router, reconnect to Wi-Fi |
Request timed out after ping |
Network is down, or replies are blocked | Check your internet connection first |
Thinking 192.168.x.x is visible online |
It is a private address | Only your public IP is seen online |
ipconfig IP differs from "what is my IP" site |
Router shares one public IP (NAT) | This is normal. See the NAT section |
| Public IP changed by itself | ISP gave a dynamic IP | Normal for home internet |
Your router shares one public IP among all your home devices.
That is why a "what is my IP" website shows a different address than ipconfig.
Two different addresses. Both are correct.
- An IP address is a device's address on a network
- IPv4: four numbers with dots (32 bits, ~4.3 billion addresses)
- IPv6: hexadecimal with colons (128 bits, almost endless)
- Public IP = your address on the internet
- Private IP = your address inside your home network
- Router shares one public IP using NAT
- Windows: ipconfig | Linux: ip addr | Public IP: curl ifconfig.me
- Test with ping (Linux: ping -c 4)
IP, Subnet, CIDR & MAC: how networks are split up, what /24 means, and how MAC addresses fit in.
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