Networking 101

How does a computer get to the internet?

I have been asked this several times. We have to fill in some gaps before I can explain the whole thing.

What is an IP address?

For your computer to run on a TCP/IP network (Internet Protocol) you need a few things on your computer. First and foremost is a network interface card or NIC for short. A network cable plugs into the NIC. It looks like a phone cable but has 8 wires inside it with a bigger connection. The other end of the cable plugs into your router, cable modem or DSL modem. That is the physical connection to the internet. Now for the complicated stuff.

Internet Protocol requires the following. An IP Address, Gateway, Netmask and DNS Servers. I like to use a little analogy when explaining this. Think of your house. Your ip address usually looks something like 192.168.1.100 The first part the 192.168.1. is your street name the last .100 is your house number. (this is only an analogy keep this in mind. It DOES NOT really mean your street) your gateway is the entrance ramp to the highway and your DNS servers are like a phone book.

If you are trying to get to another computer on your own network (another computer in your house) you would stay on the same street. So your other computer would be like 192.168.1.101 Your computer can just talk down your network home network to the 2nd computer.


The moment you want to get out on the internet you have to know the name of the place you want to go. Let's say google.com for example. When you type in google.com in your browser. Your computer looks this up in DNS (phone book) Steps 1,2,3 DNS says googles IP Address is 74.125.127.100. Steps 4,5,6 Your computer does not know where this is. So it goes to the Gateway (the on ramp for the highway.) Your gateway is your router, cable modem or DSL modem (most of the time) for this example we are going to say it your router. Step 7 So your computer asks the router if it knows where 74.125.127.100 is. Your router then looks at its IP Address. This will not be a 192.168.1 number since your router lives on a different street.. it live on your internet providers network. Your router checks with your ISP's gateway and says do you know where 74.125.127.100 is and so on until the request makes it to the correct location. Steps 8,9,10 For the google page to load the google web server has to send the data back in the exact same way it came. Although it may take a different path (road) to get back. It all depends on what routers answer first. Steps 11,12,13 and 14



I know this can be a lot to take in. It was very difficult to try and squeeze it into 1 blog posting. We do offer FREE computer classes where we can take a little more time to explain.

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