IP Addresses: A Primer
Most people have heard the phrase “IP address” on TV crime shows or while diagnosing a tech issue, but if you think about it longer, you may find you have questions. “What even are IP addresses? Where do they come from? What do they mean?”
There’s a lot of misinformation tied to that term arising from changes in technology and commonly held assumptions. Let’s check some of the facts around IP addresses.
What is an IP Address?
An IP, short for “Internet Protocol”, address is simply a set of numbers used to identify computers on the internet. The IP address of each computer on the Internet is unique at any given time. However, the IP address of a computer can change.
While some businesses and servers have permanently assigned, or static, IP addresses, most home Internet connections are given an IP address that may frequently change, a dynamic IP address. These are assigned to users by their ISP (Internet service provider), such as Comcast or Spectrum, when their internet router connects to the internet.
Public vs Private IP Addresses
The IP address assigned by the ISP to a customer is considered a Public IP address. These public IP addresses are visible to all other computers on the Internet and are necessary to allow you to access the Internet.. What if you need access to a device, like an office printer, without exposing it to the internet? In this case, you would use a private IP address. Private IP addresses use special ranges of numbers and are used to communicate within private networks, such as homes or businesses. Many computers or devices on a private network may access the public Internet through a single public IP address.
When you connect your computer to your home WiFi,, your computer is assigned a private IP address from your Wi-Fi router. The router then forwards your messages to the Internet using the public IP address assigned to it by your ISP. That’s why the IP address you can see in your computer settings may differ from the one reported by websites like whatismyipaddress.com. At your house, your phone, your printer, your TV, your spouse’s laptop, and your kid’s iPad will all look like they have the same IP address to the outside world if they use the same Wi-Fi network.
A good way to think of this is to compare it to staying in a hotel and receiving mail there. Mail might be sent to you at the hotel, but only the hotel knows what room you are staying in. The hotel receives a letter for you, the front desk checks their records to find your room number and forwards the letter to your room. Your room number is like a private IP address. If your home network is like a hotel, then each of your devices has its own room number.
You can identify a person based on an IP address.
IP addresses are not typically associated with one individual. There are too many people using the internet on too many devices for internet service providers to assign static, or permanent IP addresses. In fact, you may have heard of IPv6 addresses – these longer, more complex addresses have more possible permutations than traditional IPv4 addresses, preventing users from running out of room to connect!
You can identify a physical address based on an IP address.
An “IP address” isn’t really a physical address. Public IP addresses are checked out or borrowed from an ISP when a subscriber connects to the Internet. This is known as dynamic assignment. That means that the IP address you use today could be the IP address your neighbor uses tomorrow. You would have to request records from the ISP to determine who was using a specific IP address at a particular time.
People confuse IP addresses with physical addresses because of “static” assignment, which is when each device has a permanent address. Static assignment may occur within private home networks managed by your router, but is most commonly seen for resources on the web. For instance, Google owns a set of public IP addresses. They may assign one address to a Gmail server and then never change it.
Identification Using IP Addresses
While IP addresses cannot provide exact location data, like a physical mailing address, they can be used to identify whether the device using it is likely in a particular city or region. This is because IP address ranges are often associated with particular internet service providers who operate in a limited area. They will assign certain blocks of IP addresses to their subscribers in one area and third-party services can look-up those IP addresses and determine likely locations based on their historical assignment.
The public IP address from internet records only indicates which subscriber’s network was used for a connection – within that network there can be multiple individuals, even thousands of people, using that same public IP address. It may be possible to analyze logs within the private network to determine what devices were connected to the internet and when.