What is a dynamic IP address?

Devices like computers, laptops, smart­phones and servers need an IP address to com­mu­ni­cate and exchange data. IP addresses can be static, in other words permanent, and others are dynamic, which are tem­porar­i­ly assigned au­to­mat­i­cal­ly for a short time by a DHCP server. With dynamic IP addresses, there are some ad­van­tages such as being easier to create and greater data pro­tec­tion.

You might already know this one: Just like a telephone number or a postal address an IP address is used to identify end devices with internet access such as computers, laptops, smart­phones, servers and pe­riph­er­al devices. Without IP addresses it would be im­pos­si­ble for devices to com­mu­ni­cate since the servers wouldn’t know where to send the data. An IP address is a simple series of numbers assigned to devices in TCP-IP networks.

Dynamic IPs are par­tic­u­lar­ly common since we use a lot of devices which will often switch their network or do not have one specific function like printers or scanners. Provided you don’t regularly access an external private network or home computer, there is nothing wrong with your device regularly changing its IP address. A dynamic IP is often assigned by standard from the DCHP server of your internet provider when you go online. On home or company networks the router assigns the dynamic IP address to non-permanent devices.

An important part of IP addresses is the dif­fer­ence between static and dynamic IPs. Since every internet-capable device gets an IP address assigned to it, you will have either a static or a dynamic IP. Static IPs are also known as dedicated IPs. There are also subforms such as floating IPs which differ to dynamic IPs in that they are publicly visible but are not au­to­mat­i­cal­ly assigned.

It’s hard to define which is the best type of IP address. Static IP addresses don’t change once they have been assigned to an internet-capable, active device on a network. For this reason, they are mostly used for servers or devices which need a permanent address such as scanners and printers, keyboards or speakers. Dynamic IP addresses are assigned from a pool and include values such as the IP address, the subnet mask, standard gateway and server name. Devices which don’t need to be per­ma­nent­ly addressed will change regularly and on networks which don’t require an un­change­able identity will receive a dynamic IP.

In the past, dynamic IP addresses changed au­to­mat­i­cal­ly at least every 24 hours. Today they are only updated when the router re­con­nects with the internet. While dynamic IP addresses offer more anonymity for devices and people by changing the IP, there are questions when it comes to data privacy. Some providers also regularly save dynamic IP addresses and the personal data linked to them for more than the time tech­ni­cal­ly necessary for the user and website to be connected.

Although dynamic IP addresses can be classed as personal data, the Court of Justice of the European Union decided in 2017 that those operating sites may store the dynamic internet protocols for longer due to the risk. While there is no official ruling on this in the US, it is important to note this if you have any European clients.

The European Court of Justice has already decided in 2016 that dynamic IP addresses include personal data. This is seen as when website providers have the legal pos­si­bil­i­ty of iden­ti­fy­ing users from a dynamic IP address. These pos­si­bil­i­ties normally come with support from law en­force­ment agencies.

The following legal data pro­tec­tion prin­ci­ples are set out per the European Court of Justice:

• Dynamic IP addresses may be classed as personal data since it may be possible to identify users.
• This means that the GDPR applies to dynamic IPs.
• Saving dynamic IPs for security reasons for longer than is tech­ni­cal­ly necessary without the consent of users is not allowed without their knowledge.

If a dynamic IP has been stored without consent and for longer than needed is decided on a case-by-case basis. This is also because those operating a website should always show a data pro­tec­tion notice in order to avoid breaking any laws and being sanc­tioned.

To find out whether you're using a static or dynamic IP address, you can find your IP address. To do this on w Windows system, use the shortcut [Windows] + [R] to open the command box and enter the CMD command “cmd” and press [Ctrl] + [Shift] + [Enter]. Then you can enter the command “ipconfig/all”. This will give you all in­for­ma­tion and settings about your network adapters and your IP address.

To dif­fer­en­ti­ate between a static and dynamic IP address there are two important values:

• IPv4-Adresse: This is the IP address currently assigned to the device you are using.
• DHCP enabled: This shows whether you are using a static or dynamic IP. If there is Yes here then you are using a dynamic IP address.

When using a macOS go to your “Network settings” and click on the network you are using. Go to the “Advanced” tab and to “TCP/IP”. If DHCIP is used there to create the IPv4 then you have a dynamic IP address.

A dynamic IP address has the following ad­van­tages:

• Simple, quick and automatic as­sign­ment of the IP.
• Saves costs since they are not ad­di­tion­al­ly requested, rather assigned au­to­mat­i­cal­ly and for free by the provider or router.
• IPs can be used again since there is a selection of them.
• No IP will be doubled up on.
• No errors when assigning with incorrect IP char­ac­ters.
• More security and anonymity since the IPs are not assigned per­ma­nent­ly and devices are harder to identify by attackers.
• Iden­ti­fy­ing personal data in con­nec­tion with a dynamic IP is much harder.

There are some dis­ad­van­tages to a dynamic IP address:

• Remote access to the devices on a private or business network can be more difficult (this is where static IPs are better).
• Using hosted services such as websites or email servers can be made more difficult or stopped (again where a static IP is better).
• Device location data can be less specific since dynamic IPs may not be in the same place when moving locations.