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General Router FAQ Dynamic DNS (DDNS)

What is Dynamic DNS Setup (DDNS) ?

When you connect to your ISP, by broadband or ISDN you are normally allocated an dynamic IP address. i.e. the public IP address your router is allocated changes each time you connect to the ISP. If you want to run a local server, remote users cannot predict your current IP address to find you.

There are various free services on the Internet which offer a Dynamic DNS service. Once registered, you have a name such as myhostname.dyndns.org. This is mapped to your current IP address so remote users/computers can get to your network via that address. The DrayTek Vigor range includes an "IP poster" facility which will automatically update a Dynamic IP service with your current IP address. Compatibility is provided with the most popular services available. This is configured from the Dynamic DNS Setup menu. Check that you enter the correct data for the hostname and username - these do vary with each service, sometimes including the domain suffix.

Once set up, you can check the update status of your service from the web interface or the router's Telnet interface (use Windows telnet.exe for example). The command ddns log shows the results. Here is an example, in this case using dyndns.org :

vigor2200> ddns log
###  1 DDNS is updating ...
>>>  2 A= username H= hostname, U= 1
>>>  3 Connecting to the DDNS server (0x4225dad2)...
<<<  4 Return Code= nochg 213.113.105.12 (hostname.dyndns.org)
vigor2200>    

Note that there are three 'profiles' in the router, to allow for three different DDNS services. If you don't use any of the accounts profiles, they obviously won't update - they will show 'disabled' in the logs.

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