Getting an IP automatically | Home Network

In the previous post our home networking series, we have had an overall of what IP address is and how we can find out our own IP address when we are connected to the Internet. But if you think about it, if there are so many computers on the Internet, how does each machine get its own IP address and who gives them ? How about those on our home computer network ? Do we have to manually assign IP address to each of them ?

If you are connected to the Internet directly, I want you to try this exercise. For a couple of days, try to find out your IP address. After you turn off your computer, find out your IP address again. Chances are your IP address is not the same. Have you ever wondered why that is so ? And who gives you the IP address and how do they know when to give you your IP address ?

The answer lies in an Internet technology called DHCP or Dynamic Host Configuration Protocol. What this protocol does is that it automatically issues IP address to valid computers which ask it for an IP address. The administrator sets up a range of IP address for the DHCP to use. When a computer joins the network, it asks the entire network to give it an IP address. The DHCP server will respond to this computer and gives it an IP address.

The range of IP that an administrator might set may be a private network range in the case of a home network such as 192.168.0.1 - 192.168.0.10 or it may be a bigger range in the case of an Internet service provider like AOL.

If you are in your home network and you can get an IP address automatically, it can either be that you are connected directly through a Cable Modem or an ADSL modem which talks to your Internet service provider router which gives you an IP address. However, if you are behind a home network router, your router may have DHCP built in.

What your router is actually doing is it is giving your PC an IP address within its configured range of IP address inside the router. Most probably it will start with 192.168.0.X. Most of the home network routers on the market has DHCP functionality and if there's any PC on your home network that requires an IP address to get onto the Internet, your router will issue an IP address to that computer.

One thing to take note is that most of the people who own a home network router bought the router with the wireless capability. This is highly convenient for the user because he can move around the house and still have an IP address to be connected to the Internet. One danger is that if you do not secure or set a WEP key password to your router, the router will assume everyone who joins you network can use your Internet access, this will also mean your neighbour or any passer bys. This is very important. YOU HAVE TO SECURE YOUR WIRELESS NETWORK !

In the next instalment, we will look at how a router actually works and how does it know which PC request for what information on the Internet even if there are more then 1 computer in your home network.