How Does Dynamic DNS Work?

A question we’re often asked by our customers is how does DDNS work?

Most people have dynamic IP addresses, which makes it difficult to access their network, website, or every-day devices (such as a home file server,  home automation system, or security camera).  To solve this issue, a DDNS service (Dynamic Domain Name Service) can supply a continually updated address, allowing the user to type in a constant, static, easy-to-remember name that ensures they will be connected.

What is a Domain Name Service?  DNS is like a white pages directory for the Internet. You supply a name, it supplies a number. The name, in this case, is specifically a hostname and the number is an IP address.

So how does it work?  Here’s an example:

John has a computer with a dynamic IP address running a webserver, and his friend Jane wants to see his web page.

1) John tells Jane that the hostname of his computer is Jane types into her browser.

2) Her computer then contacts her ISPs DNS server to get the number for

3) Her ISP’s DNS server asks No-IP for the address of

4) She receives the number and connects to John’s web page.

5) To be sure Jane got the right number, John has an update client provided by No-IP running on his computer. This update client informs when his IP address changes so that Jane will get the right number. It assures that John’s often changing Internet address, his IP address, can always be found by Jane when she uses as the hostname.


  1. Must enjoy the effort you put into this blog 🙂

  2. Ajmal Khan

    dear sir
    I have open account with and want to use this account of as a remote desktop tried several times but no responce.
    Normally I can connect with remote desktop connection but with I can’t.
    Kindly send me the procedure so that I can use and help my brother.
    I will be very grateful for you in this respect.
    Ajmal Khan

  3. Paul

    I just created a host, but the host doesn’t update my IP-Adress. When I logon to your page I can see my correct hostname and the correct IP-adress in the right upper corner, but when I go on mange my host I still see the old IP-adress at the time when I created my host, no change at all, the old IP remains.
    What to do??
    Regards Paul

  4. Chris

    does my computer have to be on 24 hours a day to keep my IP updated?

  5. If you would like round the clock updates of your dynamic IP address, then yes, your computer will have to run 24 hours a day…

  6. Paul,
    This could be a stale dns on your side. You can clear your browser cache to solve the issue.

  7. john

    Hello Mme,
    I’m a new user of no-ip service and I would like know what can I do if once I finished my router’s configuration to view my lacie network space on the internet from another pc witch is located in another place than my office.
    Thank you so much for your attention!

    Best regards


  8. Good post.Ne’er knew this, thanks for letting me know.

  9. Simon

    does your DUC program do the same thing that the router does if you fill out the DDNS setting on the router with DDNS providers details
    the router logs in with user name and password and updates ip address to DDNS provider
    meaning no need to leave computer on
    however no.ip is not one of the listed providers!
    is there a way round this

  10. niko

    what do i do if my pc block acces to my ports?
    I use school pc and it wont let me port forward ( shutdown firewall doesn’t work )

  11. Please open a support ticket and we will be happy to help you!

  12. luis marques

    activei uma conta mas a outra pessoa nao consegue visualisar , o computador tem de tar 24h ligado?

  13. i had install cctv in my office. How can I view my cctv at my house?

  14. Paulo Faria

    Boa tarde, tenho um video de vigilância e gostaria de saber como fazer para aceder ao mesmo remotamente.

  15. Hello,

    I’m using Web Redirect as Host Type for this site but nobody can access it outside my local network. I’m using No-IP Duc, port 80 is open (says my ISP) but all you get is the Page Title at the top and the white bar at the bottom with «Free Dynamic DNS and Port 80 Redirection Provided by» but nothing in between and a message finally tells you the page can’t be found.

    Can you help?

  16. Can you please open a support ticket? Thanks!

  17. MikeD

    So, from what I understand No-IP will remove an account/hostname if there are no updates to the record in 30 days. The problem is, my ISP will rarely change the IP address if the modem has not been power cycled. My IP has been the same for sometimes over 6 months.

    I am using a QNap and have it configured with NO-IP as the Dynamic DNS provider. It appears that it will only contact NO-IP if the address changes. In this situation will my entry be removed?


  18. Yes, unfortunately it will be removed since we won’t see an IP change. You will need to confirm your hostname via the monthly email we send, or you can upgrade to Enhanced Dynamic DNS and it will remove this requirement.

  19. i want to put 5 cameras on the web.. 3 x PTZ, to view livestock in my barn, one static in my owl box, and one that is switched on occasionally for veterinary purposes.

    How will dynamic DNS help me to share those cameras?

  20. If you have dynamic IP addresses at those locations, our service will help you easily log on to view the cameras from an easy to remember URL. (example your cameras will need to support our dynamic DNS in order to update the IP address correctly. If not, you will need a computer at the location with our Dynamic Update Client installed. This will keep the hostname active with the current IP address.

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