Sales Loves MarketingAn IP address is the numeric label a device gets when it joins a network that uses the Internet Protocol. It does two jobs: it identifies the device, and it tells the network where to send data for it. A common example is 192.168.1.1.
How do IP addresses work?
Every request on the internet carries two IP addresses: where it came from and where it is going. When you open a web page, your device sends a request from its IP address to the IP address of the server. The server sends the page back to your address. DNS is the system that turns a readable domain name into the IP address of the server behind it.
There are two versions in use:
- IPv4 addresses are 32 bits long and written as four numbers from 0 to 255, such as 192.168.1.1. That allows about 4.3 billion addresses, and the supply ran short during the 2010s.
- IPv6 addresses are 128 bits long, written in hexadecimal, and give a vastly larger supply. The current IPv6 standard is RFC 8200 from 2017.
Who assigns IP addresses?
The Internet Assigned Numbers Authority (IANA) coordinates IP addresses worldwide. It gives blocks of addresses to five regional internet registries: AFRINIC, APNIC, ARIN, LACNIC and RIPE NCC. They pass them on to internet providers and organisations, which assign them to devices.
Addresses can be:
- Static, set once and kept, which is typical for servers.
- Dynamic, handed out each time a device connects, usually by DHCP. Most home and office devices work this way.
- Private, used only inside a local network. The ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for this. Your router shares one public address between them.
Your device's network settings show its private (local) address. Websites only see the public address of your network.
Why do IP addresses matter in marketing?
Email deliverability. Mailbox providers judge the IP address that sends your mail. Google's sender guidelines say the sending server's IP must have a reverse DNS (PTR) record, and that on a shared IP "the activity of any senders" affects the reputation of all of them. They also advise starting new sending at low volume to engaged contacts and increasing slowly. See deliverability and sender score.
Analytics and visitor identification. Google Analytics derives coarse location, such as country, region and city, from visitors' IP addresses. Its help pages say that for EU, Swiss and UK users the IP address is used only for this and then discarded. Location data like this supports geo-targeting. Some B2B tools try to match the IP address of a business network to the company that owns it, to show which companies visited your site. See how to identify ABM leads on your website.
Privacy law. GDPR Recital 30 names "internet protocol addresses" as online identifiers that can be combined with other data to profile and identify people. Collect, store and share IP addresses with the same care as other personal data, and cover them in your privacy notice. See GDPR.
Frequently asked questions
What is the difference between IPv4 and IPv6?
IPv4 addresses are 32 bits long, which allows about 4.3 billion addresses, and are written as four numbers such as 192.168.1.1. IPv6 addresses are 128 bits long, which gives far more addresses. IPv6 was created because the IPv4 supply ran short as the internet grew.
Is an IP address personal data under GDPR?
It can be. GDPR Recital 30 names internet protocol addresses as online identifiers that, combined with other information, can be used to profile and identify people. Treat IP addresses in analytics and marketing tools as personal data unless your legal team says otherwise.
Why does my sending IP address matter for email marketing?
Mailbox providers judge the IP address that sends your email. Google's sender guidelines say every sender on a shared IP affects that IP's reputation, and that the sending IP needs a valid reverse DNS (PTR) record.