What is a Dynamic IP Address?

We get this question a lot from users, so I think it is fair to touch on it quite often.

First, let’s explain what an IP address is. An Internet Protocal Address or IP address for short, is like your computers phone number. Without it, your computer wouldn’t be able to connect to the Internet. Every computer, tablet, smart phone, and internet enabled device has it’s own IP address (even some light bulbs have an IP address these days).  An IP address consists of numbers and periods (

So, what is a dynamic IP address? Well, a dynamic IP address is one that changes from time to time and isn’t always the same. If you have a  residential cable or DSL service, you most likely have a dynamic IP address. Internet Service Providers (ISPs) provide customers with a dynamic IP addresses because they are more cost effective. Instead of one IP address always being yours (static IP address), your IP address is pulled from a pool of addresses and then assigned to you. After a few days, weeks or sometimes even months, that number gets put back into the pool of numbers and you are assigned a new number.

This is why a dynamic IP address can make it tricky to remotely access your PC, DVR or webcam, because even if you know your IP address at this moment, 5 minutes from now it could be different. So if you are away and want to access your computer remotely, but you have the wrong IP address, you will not be able to connect to your computer.

Dynamic DNS makes a dynamic IP address act as though it’s static (does not change) even though it is not.  With No-IP you create an easy to remember hostname. This hostname is the URL that you type into your browser to connect to your remote device. Our Dynamic Update Client takes your hostname that you created (yourname.no-ip.org) and points it to your IP address. When your IP address changes, our Dynamic Update Client updates your IP address on our servers, therefore your hostname stays active with your active IP address and your connection stays available all the time.

Sometimes, routers have dynamic DNS or DDNS built into the router. With this feature, you do not need to download our Dynamic Update Client. You will just need to log in to the admin settings on your router and configure it with your No-IP username, password and hostname. This will keep your connection active for you automatically.

Dynamic IP addresses are a bit annoying, but with the right software you can get around them easily and for free. Most ISPs will not provide a static IP address to residential customers and if they do, they are often very expensive.

Additional questions or comments? Leave them below!

  1. The problem with routers having built-in DDNS is sometimes it’s not the service you already have. A ZyXEL 5000Z router (Some might know it as a Quest DSL modem) uses DynDNS. Your No-IP user and password will not work. Ensure your router uses No-IP before using your router’s DDNS option. DynDNS no longer offers a limited amount of free hosts. It is now 100% commercial. Those who managed to get an account with DynDNS for free, remain free. This is also why No-IP is still the better choice. If your router doesn’t support No-IP, just stick with using No-IP’s Dynamic Update Client on your computer.

  2. That’s a great point to add Mark, Thanks! Hopefully more router companies will realize this and start supporting No-IP for dynamic dns.

  3. Matthew

    Would you be able to post a list of routers that do work with

    Would make life soooo easy!

  4. I will compile a list of routers and post it! Thank you for the suggestion!

  5. penguintamer

    I like the analogy “An Internet Protocal Address or IP address for short, is like your computers phone number”. I’d follow it up with something like, “You wouldn’t want your phone number to change every day, but that’s exactly what happens to your computer with dynamic IP addressing.”

  6. Erwin

    Hello, I have one of Fritz’s box AVM in 7270 as a Router, have there at the beginning of the year NO ip as dyndns has furnished always well functioned only I have in the last time whenever I from outside on it there would always like to access connecting mistake. Does somebody maybe have a solution?
    Lg Erwin

  7. that’s a great idea! thank you for sharing!

  8. kavya m

    I have one doubt , kindly clear it.
    Once the computer is turned on & accessing the internet, the dynamic IP address allocated at this time to home computer will remain same till the internet connection is turned off or it`ll keep changing till it s turned off ?

  9. No, your dynamic IP address can change at anytime. It depends on your internet service provider and your router. Some IP addresses change a few times a day, or a few times a year. It really just depends on your ISP.

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