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What is an IP Address?

An Internet Protocol (IP) address functions a lot like a real-world home or return address on mail. An IP address is assigned to your computer or laptop by your Internet Service Provider (ISP) through your router. More specifically: your router will assign each device accessing the internet through it an individual local IP address, but on the internet each of the devices will display the same online IP address.

How does it work?

Like a home address, it is used by the receiver of your information to send information back to you. You ‘mail’ your login details to a website, the website then checks this information and sends the relevant information, a successful or failed login in this instance, back to your IP address where you will receive this information on your Personal Computer (PC) or laptop. If multiple PC’s or laptops are accessing your home internet, the router will then use your device’s local IP address to make sure it gets back to you and not another device accessing the internet through the same modem.

Types of IP Address

There are two types of IP address: static and dynamic. A static IP address is one that you configure yourself by editing your computer’s network settings. This is the rarer of the two and can create network issues if done without a keen knowledge of IP (Internet Protocol). Dynamic addresses are far more common. They’re assigned by the Dynamic Host Configuration Protocol (DHCP), a service running on your home network. A DHCP is most commonly run on network hardware such as a router or a dedicated DHCP server. In most households, the former will be the case, with the router assigning local and internet IP addresses.

Everyday usage

Whether sending an E-Mail, logging-in to a website or entering in payment and shipping details, your information request needs to be sent to the right destination, and the response information needs to come back to you. IP addresses make this happen.

As previously mentioned, an IP address is assigned to your home computer by your Internet Service Provider (ISP). Since ISP’s give you access to the Internet, it is their role to assign an IP address to your computer. Every information and access request is sent through them, and they know to route it back to you specifically by using your IP address.

IP addresses differ from a home address in some ways though. Unlike your home address, your IP address can change. Something as simple as turning your modem or router on and off will change your IP address, and you can even contact your Internet service provider and have them change it for you, should the need arrive.

It stays at home

Much like your home address, you don’t take your IP address around with you. If you check your IP address at home, it will (mostly) stay the same; take your laptop to your local coffee shop and hop on their Wi-Fi and you’ll notice that your IP address is different. Furthermore, unlike at home where your IP address will normally stay the same, your IP address at the coffee shop will likely be different each time. This is because public Wi-Fi systems assign a random, non-unique, temporary IP address to a user each time they access it. Once you’ve left the coffee shop, your laptop leaves that IP address with it.

IP addresses and websites

Every domain has an IP address assigned to it. However, these IP addresses are usually not unique. FQDN’s (Fully Qualified Domain Names) were developed as a means for web hosting servers to handle the ever-increasing number of websites in need of a unique address. Aside from FQDN’s, there are dedicated IP addresses which are unique Internet addresses assigned exclusively to a single hosting account. Shared hosting accounts share a server’s IP address and cannot have a dedicated IP. For instance: www.example.com, random.org and infinitum.net could all be on a shared hosting account, sharing the same IP address 123.45.67.89 – it is their FQDN that points visitors toward their website. However, large amounts of traffic to www.example.com and random.org can negatively affect infinitum.net’s user speed due to so much traffic on the shared IP address. This is where dedicated IP addresses come in handy. They are completely unique, only your FQDN uses that IP address, so traffic on other websites can never influence your website. A dedicated IP address also lets people visit your website by typing in your IP address into the search bar, instead of the FQDN – however, this isn’t a particularly useful feature as FQDN’s are easier to memorize and type than an IP address.

IP and SSL

SSL Certificates were once able to be issued to IP addresses, but a CA/B Forum (Certificate Authority Browser Forum) guideline effective from October 1st 2016 saw this practice banned by all trusted Certificate Authorities (CA). This is because, as previously mentioned, non-dedicated IP addresses are not unique, thus a person could have a CA issue them a copy Certificate of an IP address and use it for intercepting transmissions. It was also once the case that a website needed a dedicated IP in order to install an SSL Certificate. This is no longer the case – a website’s IP address could change 100 times in a day without affecting its SSL Certificate. Nowadays, all that is required to have an SSL Certificate issued to a website is a Fully Qualified Domain Name (FQDN).  

Updated on July 24, 2019

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