Imagine This

You want to send a letter to your friend so you write your message and put it in an envelope. Next you need to add an address so it goes to the right person - but pretend you don't already know that. What are you going to do?

You will use their name, for example, "Richard Hendricks" and look up their address (maybe in a phone book but probably online...). Once you put the right address, USPS knows exactly where to take your letter.

IP addresses and DNS work just the same way!

• When you type "google.com" into your internet browser, your browser reaches out to a "DNS Server" which is like that phone book, it is going to take in "google.com" and sends back the actual address that the browser needs to travel to to get the information it is looking for

• The address that is returned is an IP Address, you have probably seen these before. They look like "192.168.1.1" - this is the actual address your browser needs to load information. "Google.com" doesn't mean anything to a browser unless it can reach a DNS Server to look up the actual address

Then what is a "port"?

If your IP address is your "Address" on the internet, the port number they use is like the "PO Box". It is a more exact address. If a certain port is required for messages but gets blocked for some reason like parental controls, messages will not be delivered!

Quick Definitions

IP Address - The real address a device or app needs to connect with the information you are trying to load. Looks like "192.168.1.1"

DNS Server - A server that translates a web address (a.k.a. "URL") like Google.com into the IP Address the device needs

Ports - A more specific address required for communications. Ports 80 and 443 are two of the most common examples.

IP addresses are required to talk to any server or device over the internet but there are also "private" IP addresses as well

Public vs. Private IP addresses

Public IPs are IP addresses you can look up via the DNS server. Your home would have a single Public IP, for example 173.45.169.111. Public IPs are unique - otherwise messages would be delivered to the wrong place!

Alternately, each of my devices that are on the internet have their own Private IP, for example 192.168.1.1 (a common IP for routers). These are used within my home network to get messages to the right individual device, but can be duplicated inside other home networks. Both me and my friend could have a device with Private IP 192.168.1.1 because they are not shared outside of our homes! As well, each device in my home has Ports as well (discussed above).

Now we have all the information we need to get the full address needed to talk to a specific device on a network!

Take a second now to think about how you would "address" a digital letter using the concepts of DNS Servers, Public IP, Private IP, and Ports.

You only would use a DNS Server to get the public IP needed! Then you would address the letter like this:

Public IP (the home network)

Private IP (the device)

Port (a specific "PO box" for the device)

This article comes from our RouteThis Academy: Home Networking 101 lesson.