Are IP Addresses Unique

If you start researching about how the internet works and specifically communicates then you’ll end up reading about TCP/IP.   This stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols which allow network devices to communicate with each other.  More importantly to most of us, TCP/IP is the networking standard on which something rather important is built – the Internet.

The internet doesn’t work without TCP/IP and for any device to communicate online it requires something important called an IP address.  This is simply a a number or address which is assigned to each and every device on the internet in order for it to send and receive data over the network.  It can be thought of as the digital equivalent of  your postal address and the data simply as mail which is delivered here.  So you won’t be surprised to hear that for the internet to work properly these digital IP addresses need to be unique.

Are IP Addresses Unique

This is a point which makes perfect sense after all if you had duplicate addresses how would the data reach it’s correct target.  However when you start learning about this stuff it’s often a source of confusion.   For example if you order a new router or get one supplied by your ISP company, there’s a very high chance that it’s assigned an IP address like  Perhaps the router you have installed has this address, mine certainly has.  Indeed it’s almost certain that there are millions of routers and Wifi Access points all over the world with the identical IP address of  It’s often used as a standard default by hardware manufacturers.

So if there’s millions of routers connected to the internet, they’re obviously not unique !

Absolutely, and this is where the confusion often arrives.  IP addresses on the internet must be unique, however these routers can have multiple IP addresses.   So what’s going on, how can this be?   Well, the important distinction to remember is that on the internet there are two type of IP address ranges – Public and Private.  The private address ranges are defined here – RFC 1918  and actually stipulate IP addresses which you can use on private networks.  That is you can use the IP addresses on devices in internal networks which aren’t accessible from outside.  No-one else can access these addresses outside that specific network so there’s no issue with the addresses being used on multiple devices.

Of course, this means that a private IP address isn’t sufficient to allow access to the internet.  Clearly your home router needs to reach the internet, so it needs a second IP address that is genuinely unique.  These are called public IP addresses and most people’s routers will have one of these as well.   This can get a little bit confusing but it’s actually fairly straight forward, just remember there are –

  • Private Addresses – which can only be used on an internal network like your home or Office LAN.  These addresses are not visible over the internet and therefore there can be many duplicates globally (but not on the same network!).  Also frequently referred to as internal addresses.
  • Public Addresses – are unique and required for every device connected to the internet.  Usually assigned by your ISP (Internet Service Provider) for home users but also can be from mobile networks for your phones address. Also referred to as internet facing addresses.

Generally if you see a discussion about IP addresses related to proxies, privacy, gaming, access to geo-blocked sites then it’s almost certainly about public IP addresses.   These are the important addresses which shape your online experience, the private addresses are not unique and cannot be seen by anyone.  They are unique and there are a limited number of them available.

If Supply is Limited Will We Run Out of IP Addresses ?

This is actually quite a common story, a sort of digital apocalypse where the entire internet stops working because we’ve run out of IP addresses for devices.   Rumors have abounded about this over the last few years and you’ll still find lots of articles predicting this is going to happen around 2020 all over the web.  However before you starting to worry about this, it’s best to check the date because it’s not really of that much concern anymore.

It’s true there’s a limited number of IPV4 IP addresses  which are the ones usually used to connect to the internet. However although technically every IP address does need to be unique, there’s now much more leeway because of the way we can use public and private IP addresses.

For example in my house probably like most, there’s a myriad of devices which need an IP address to connect tot he internet. Medias streamers, games consoles, tablets, laptops etc the list seems to grow every month. However twenty plus devices in my home operate with only a single public IP address which can potentially handle many, many more. This is because my router can keep these two networks separate and ensure that my one single public IP address is sufficient. It controls the data on the ‘private side’ of my network sending the data to whichever device needs it.

Anybody can potentially do this, indeed your router or access point is probably doing it already.  By using both private and public addresses, a single IP address can split into up to 16 million new ones.  It’s of course something of a workaround as each device does not really have a genuinely unique IP address.  However it’s a perfectly good workaround until the situation changes.

The lack of IPV4 IP addresses will eventually be solved when we complete the transition to IPV6 address ranges.  This will unleash rather more unique IP addresses that we can use because of the length of the addresses.  Version 4 addresses are 32 digits long and allows a total of 4.2 billion addresses to be used (which sounded a lot in the 1990s!) . The new version IPV6 has 128 digits which means we have 2 to the power of 128 combinations available to assign addresses to.

This apparently  is 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses or 340 undecillion in total – a number so amazingly large, I’m sure it will suffice for a few years !

A Final Point regarding Residential Proxies

Unfortunately this doesn’t mean that we can set up our own residential proxy server with a few million IP addresses at home.  At least not with regards hiding our identity and location, because ultimately  the single internet facing address will be the one the outside world sees.   So we can assign as many private IP addresses to our devices  however when we visit a website then they will all be allocated against our public address.