DDNS Updater

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Installation

Download and run the .msi file to install DDNS Updater. After installation, you're presented with the option to configure DDNS Updater.

At its simplest, you only need to enter a value for the IPv4 (or IPv6) update URL and save the settings, then DDNS Updater should work.

DDNS API

External check URL: DDNS Updater polls a URL to check whether your external IP address has changed. Any URL which returns your current IP address should work. To do an IPv6 check, enclose the host in square brackets, e.g. http://[checkip.dyndns.org]. If blank, DDNS Updater will cycle through a built-in list of URLs to find one that works; you must use the built-in list if you want to do "dual-stack" (both IPv4 and IPv6) updates. A "%IP%" in the URL will be replaced by the IPv4 address from the last DDNS update.
IPv4 update URL: Update URL for the specific DDNS service you are using. This can generally be found on their support page. Example for Zonomi:
https://zonomi.com/app/dns/dyndns.jsp?api_key=apikeyvaluehere&host=www.example.com If you need to specify the new IP in the URL, use "%IP%", but most DDNS APIs correctly assume the new IP to be the source of the API call. IPv4 updates will be disabled if this field is blank.
IPv6 update URL: Update URL for the specific DDNS service you are using. This can generally be found on their support page. Example for Zonomi:
https://zonomi.com/app/dns/dyndns.jsp?type=AAAA&value=%IP%&api_key=apikeyvaluehere&host=www.example.com If you need to specify the new IP in the URL, use "%IP%". IPv6 updates will be disabled if this field is blank.
Username: If the update URL uses basic HTTP authentication, specify the username here.
Password: If the update URL uses basic HTTP authentication, specify the password here. The password is encrypted before being stored on your computer and is safe from most 'casual' hackers, but you should use a different password to sensitive accounts such as bank accounts.
Check interval: How often (in minutes) DDNS Updater should poll to see whether the external IP has changed. You should check whether your provider's abuse policy limits the check frequency (e.g. no more than once per 10 minutes), and set this value accordingly. Some providers will block access if you check too frequently. If zero, no periodic checks will occur.
Force update: If greater than zero, this specifies the frequency (in hours) at which an "update" will be forcibly sent to the DDNS service irrespective of whether an IP change has been detected.

In most cases, only the IPv4 update URL is needed. Most ISPs using IPv6 allocate customers with a range of static addresses, meaning there is theoretically no need for a service like DDNS Updater. However, Windows does have the ability to select a random IPv6 address from a static range to help 'anonymize' web browsing, and in this case an IPv6 DDNS service may still be useful.

DDNS Updater considers an update to be 'successful' if the server returns an HTTP result code of 200 (OK). It is possible that your DDNS service specifies an error in the body of the result, but still sends an HTTP code of 200. DDNS Updater currently does not handle this situation, so please check your update URL carefully.

Logging

Log detail: The level of detail to be logged can be specified.
Log directory: Directory for log files. If blank, %TEMP%\DDNSUpdater will be used.
Log file name: File name for the log file. If blank, logging is disabled.
Max log size: When the log reaches this size (in KB), it is renamed to .bak and a new log is started. Any existing .bak is overwritten. If zero, no log rotation is performed.

SMTP server: Machine name or IP address of the outgoing SMTP server. If this is blank, email notifications are disabled.
SMTP port: The standard SMTP port is 25, but you may specify a different port here.
SMTP username: If your SMTP server requires authentication, specify the username here.
SMTP password: If your SMTP server requires authentication, specify the password here. The password is encrypted before being stored on your computer and is safe from most 'casual' hackers, but you should use a different password to sensitive accounts such as bank accounts.
Email address: Enter the email address that notifications of an IP change should be sent to. If this is blank, email notifications are disabled.
Email subject: Subject line for email notifications. This can be customized to help with filter rules.

Use the 'Test' button to send a test email using the current settings. DDNS Updater does handle encrypted SMTP connections, such as STARTTLS. However, it has not been tested with a wide variety of SMTP servers or configurations.