What is the difference between an internal IP and an external IP?

"Internal IP" is another term for a non-routable IP address. An IP address is a unique identifier on the Internet, like a telephone number, and non-routable means that a router will never forward packets to a computer or other device that has a non-routable IP address (if you don't know what a router is, find the "what is a router" question on this site).

"External IP" is another term for a routable IP address. When people talk about internal and external IPs, they are usually talking about a NAT router. NAT stands for Network Address Translation, and the form of it that most people are familiar with is the form that allows multiple computers to share a single Internet connection via one physical connection to the ISP. If you have a NAT router in your home, each computer connected to it has an internal IP, while the router itself is assigned an external IP. If you didn't have a router, the external IP would be assigned to whatever computer is connected to your ISP.

Carsomyr gives an excellent answer.
However in simpler terms:-
An external address is like a telephone number that anyone can phone.
It has to be unique (and should be allocated to you).
(Imagine if two people had the same phone number for completely different houses - who would get the call - similar problem would occur with computers with the same external number).
Using that IP address (telephone number) any other computer connected to the web can talk to you (any phone on the phone exchange can phone you), unless you limit them in some way (firewalls etc - a bit like call barring).

An internal address is more like an extension number within an office.
It is unique within that office but another office belonging to another company may have the same internal extension number. It does not have to be allocated by an external authority - it is controlled by the company itself. Depending on how things are set-up, external computers may be able to talk to your computer or may not - similar to an internal phone.

The use of internal IP addresses means we have not run out of external addresses. The number of computers connected to the web exceeds the number of external IP addresses using the original set of numbers. (This is being extended IP6).

Non routable or private IPs include:

10.0.0.0/8 (commonly used)
127.0.0.0/8 (loopback addresses)
169.254.0.0/16 (Micro$haft range)
172.16.0.0/16 (least commonly used)
192.168.0.0/24 (most commonly used)

These are USUALLY non routable because internet routers are configured to not route them. You can route them on your own network if you setup the network hardware to route them over you WAN or through your VPN tunnel.

An external/public/WAN IP is what is used out on the big bad internet.

Internal IPs are sometimes referred to as virtual IPs. They are a group of up to 255 IPs that are used and recognized internally on the local area network. They are not intended to be recognized on the Internet.Real Ip as is external ip, The real IP from ISP, instead, can be recognized or pinged by another real IP. The Prestige 310 Internet Access Sharing Router works like an intelligent router that routes between the virtual IP and the real IP.

ALL PCS HAVE INTERNAL IPS ALL ROUTERS USE THIS TO PORT OUT TO THE ROUTERS EXTERNAL IP ADRESSS.....INSTED OF USING THE WORD IP.....TRY CELL NUMBER AS THIS IS BASICALY THE COMPUTERS WAY OF CALLING OTHER COMPUTERS AND THE ROUTER IS THE TELEPHONE EXCHANGE.

Well I dont have a router, just connected straight to my modem. In order to do this

1. Go to Start. Then Run.
2. Type. C:WindowsSystem32DriversEtc
3. This will open a folder, Click on Host.file and open it with Notepad/Wordpad.
4. At the end of the file add the following.

CODE
127.0.0.1 (Dynamic DNS)
(Internal IP) (Dynamic DNS)
(External IP) (Dynamic DNS)

I need my internal ip address. But when I go to run>cmd>ipconfig /all

I get a few Ip addresses but nowehere does it show an internal. Can I just use 127.0.0.1 and it will work the same?

Internal IP is nothing but non-routable IPaddress. Where as, External IP is another term of routable IPaddress.

Internal IP is the IP assigned to you on a local area network (LAN).

External IP is the REAL IP of your internet. It's the IP that you would have if you were not in a local area network.

hey good responses...


I have a question,

How to connect to a computer remotely tht is asigned an internal ip address by a router ....

Is there any way that I Can use win-xp-prof Remote desktop tool....

please reply Thanks in advance...

enable port forwarding on the router, probably port 3389. Here will give you advice on forwarding that port on your router : http://portforward.com/

When you want to connect to your DVR remotely, you will need to use either the internal or the external IP address. This will be determined by whether you are accessing the DVR from inside the network or from outside the network. If you are accessing the DVR from inside your network then you will use the internal IP address. The internal IP address will usually begin with 192.168.XX.XXX . No port number would be used since you are connecting internally. The internal IP address can usually be found in your DVR under network settings.

To access your DVR from outside the network, you will need to use an external IP address followed by the port number to identify the DVR (unless you put the DVR on port 80). An external IP address is the IP address used to connect to your router. The port number will identify the individual device inside the network you wish to access. So an external IP address would not have 192.168 in the beginning but it could be anything else. An external IP address would be entered as XXX.XXX.XXX.XXX:port#