External vs. Internal IP Addresses: What the heck they are?

Computer NetworkIP stands for Internet Protocol which is a numerical label assigned to a technical device participating in a computer network. It is used for communication – to communicate among one another. In simple terms, if a network has two computers namely ABC and XYZ, each of them will make use of Internet Protocol (IP) addresses to identify themselves and to send and receive a set of information between them.

It means an IP address is a unique set of numbers assigned to a device to identify it on the network. The basic format of IP address is a combination of four sets of numbers separated by dots. For instance – This format of IP address is called IPv4 which is being used as a standard format since the very beginning. But as the number of computers has increased, the need of unique addresses has also grown with the same pace. It has brought us to the present day situation today where IPv4 addresses are falling short to accommodate the number of computers in the world. The total number of IPv4 addresses is close to 4.2 billion which of course is not enough to assign a unique address to every single computer in the world. This is the reason, a new version has arrived namely – Ipv6. But this new version is not very popular yet. However, it is gradually taking its pace. The format of an IPv6 is something like 2001:db8:0:1234:0:567:8:1 which if adopted completely,  every single computer in the world can have a unique external IP address.

Now, you must be wondering what an external IP address is. Okay, let me give you an example to help you understand it better. Supposing XYZ Limited has a set of 20 computers in its office, and all of these computers are connected to a single internet connection line.  Single connection means XYZ Limited has bought only one internet connection from its Internet Service Provider (ISP). Here, this single connection is being used to access internet from all 20 computers in the network. It is done with the help of a router, the connection from ISP connects to router, and then the router connects to all computers. Now, as the company has bought single connection, it will be assigned only one IP address by the ISP, this IP will be external address. It means if you check the IP of any computer, it will have the same unique number assigned by the ISP. Now the question is – ‘How will the router communicate to individual computer on the network if they all have the same address?

Well, this where an Internal Internet Protocol comes into picture. This is again a unique set of numbers that is assigned to individual computers on the network by the router. It can be in the format of So what happens if somebody tries to access this Internal IP from outside the network? Okay, in that case, that person will not be able to access the individual computer on the XYZ’s network, rather he/she will be taken to their own local network.

I hope now you have got the concept of Internal and external IP addresses. Want to know your external IP address that is visible to entire world connected to internet? Go to http://www.whatismyipaddress.com.

In one of my forthcoming blogs I will discuss how a person from outside the network can be facilitated to access a particular computer on XYZ’s internal network. What all setup needs to be done and how? For now, if you have any problem setting up the computer networks in your office or in home and you in Auckland or in the neighbouring areas, contact me today to book an appointment.

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