IP, DNS, Gateway & Subnet Mask 😳 Finally Explained Simply

The Big Picture — Four Settings Every Device Needs

Every phone, PC and printer that joins a network needs four pieces of information before it can talk to anything: its own IP address, the subnet mask, the default gateway and a DNS server. Think of it like a house in a city: the IP address is your house number, the subnet mask tells you which houses are on your own street, the gateway is the gate at the end of the street that leads to the rest of the city, and DNS is the phone book that finds an address when you only know a name. In most home and office networks your router hands out all four automatically through DHCP — but when the internet stops working, these four values are exactly what you check.

IP Address — Your Device's Own Address

An IP address is the unique number that identifies one device on a network, so data knows where to go and where replies come back. It is written as four numbers separated by dots, like 192.168.1.25 in the video's example — that is the address of one PC on a home network. Addresses starting with 192.168. are private addresses: they work only inside your own network, and every device in your home must have a different one. The router also holds one public IP address given by your internet provider, and that is the single address the whole house shares when it talks to the internet.

Subnet Mask — Who Is Local, Who Is Not

The subnet mask looks like another IP-style number — 255.255.255.0 in the example — and it has one job: it splits the IP address into the network part and the device part. With 255.255.255.0, the first three numbers name the network and the last number names the device. So 192.168.1.25 and 192.168.1.40 are on the same network — they can talk directly. But 192.168.2.10 is a different network, and traffic for it must leave through the gateway. This mask (also written /24) allows up to 254 usable device addresses on that one network, which is plenty for a home or small office.

Default Gateway — The Door to the Internet

The default gateway is the address of your router — 192.168.1.1 in the example. Your PC uses the subnet mask to decide: if the destination is on my own network, send it directly; if it is anywhere else, hand it to the gateway and let the router forward it. Every website, update and cloud service lives "anywhere else", so almost all your traffic passes through this one address. That is why a wrong or missing gateway gives the classic symptom: you can reach the printer and shared folders on your own network, but no website opens.

DNS — Names Turned Into Numbers

Computers reach each other by number, but people remember names. DNS (Domain Name System) is the internet's phone book: when you type a name like google.com, your PC first asks the DNS server "what number belongs to this name?", gets back a public IP address — a 142.250.x.x address in the video's example — and only then connects. Your DNS server is normally your router or your internet provider's server, handed to you along with the other three settings. If DNS fails while everything else is fine, websites stop opening by name even though the internet connection itself is alive — the phone book is broken, not the road.

How All Four Work Together

Now watch all four do their jobs in the two seconds after you press Enter on a website. Your PC (192.168.1.25) asks DNS for the site's number and receives its public IP. The subnet mask (255.255.255.0) tells your PC that this public IP is not on the local network. So the request goes to the default gateway (192.168.1.1), the router, which forwards it out to the internet and brings the reply back to your IP address. Remove any one of the four and the chain breaks: no IP means no identity, no mask means no local-or-remote decision, no gateway means no way out, and no DNS means no name lookup. That is the whole lesson of the video — four small values, one complete system.

Read Your Own Settings with ipconfig

You do not have to guess any of this — Windows will show you all four values on your own PC. Open Command Prompt and run the command the video uses:

ipconfig /all

In the output for your active adapter, look for the four lines — these are the example values used in the video:

IPv4 Address . . . . . . . . . . . : 192.168.1.25
Subnet Mask  . . . . . . . . . . . : 255.255.255.0
Default Gateway  . . . . . . . . . : 192.168.1.1
DNS Servers  . . . . . . . . . . . : 192.168.1.1

Read them the way the video teaches: that is my address, that is my network boundary, that is my door to the internet, and that is my phone book. Once these four lines make sense, most "internet not working" problems stop being a mystery.