Before we get into what a dynamic IP address is, let me give you a little background on the topic. First off an IP address is an Internet Protocol address. For more information on what an IP address is you can check out this page on Wikipedia. We can consider this your machine’s Internet Address.
But it gets a little more complicated when we throw dynamic IP addresses into the mix. Most of the time when you sign up for Internet service you are give a single “external IP” address. This external IP address can be split up so multiple computers or devices can get online.
You have probably see an IP address on this screen before:
The above example shows an external IP address set up. If this machine was using a dynamic IP address the check box would be checked for Obtain an IP address automatically.
When you take a external IP address and divide it up, you will use dynamic or Natted IP addresses. NAT stands for Network Address translation – translating one external address into multiple internal addresses. You can use a service called DHCP to assign computers dynamic IP addresses automatically when they start up.
Below you can see a basic diagram showing how a network is set up and operates. You will see the cable modem gets a Internet Address and the router assigns internal addresses, yet all the equipment on this home network can connect to the Internet. If you open up a browser and go to WhatIsMyIP all the machines will tell you they have the same external IP address.
In most homes we have a router connected to our internet modems. Some Internet Service Providers will give you a modem with a built in router. If this is your case you can imagine that the modem and the router is one unit. We will still refer to it as a router or as a modem. Just know that we are talking about the same thing in your situation. Here is an example of what a modem looks like:
This router is what does your Network address translation and assigns your computer or computer’s dynamic IP addresses. Without the router in place you would not be able to use your Dynamic IP address on the Internet. That is because these groups of dynamic IP addresses like 192.168.0.1 are reserved for internal networks.
You can see an example of what a router looks like here:
Chances are if you are reading this post you are not getting your dynamic IP address assigned to you. The first thing to do is make sure all your network equipment is turned on. This includes your Internet modem provided by your ISP, your router and if you are using a laptop and a built in Network Interface Adapter you will need to have your power cord connected as well.
If everything is plugged in the next thing to do would be to check your status lights on your modem. Are they all green? Do they say you are connected? They should look like the example of the modem two pictures up. If they do, this part is good and you can continue on to the next piece of your network. That is probably going to be your router. Are the lights blinking? Is there a connected or internet Led? Does it say you are connected? If not or you cannot determine this, you should reboot it. Simply pull the power cord and wait 5 seconds and then re-plug it in.
If this fixed the issue, your computer will tell you that it is obtaining an IP address and then it will tell you that it is connected.
We can think about an internal IP address as a extension on a company phone network. If you just dialed that number from your home you would not get connected. But if you dial the main company number and then the extension you will get connected. Just as a dynamic IP address could only be referred to on that network.
We have done quite a few router articles in the past including the following :
How To Secure Your D-Link Wireless Router – Susan
8 Tips To Effectively Boost Your Wireless Router Signal – Leon
Technology Explained: How Does a Router Work? – Guy
How To Turn An Old Router Into A Wireless Bridge – Jorge
I would love to field questions so if you have any please feel free to leave them in the comments!