To ensure fair use of our systems for the general public, client authors must ensure that clients follow these policies. Clients that do not comply with these policies may be blocked from accessing our systems.

Required Client Behavior

• Send a unique user agent which includes company name, model number, and software build revision.
• Check that all input is in valid form before updating.
• Check that any IP obtained through web-based IP detection is a valid dotted quad numeric IP (e.g.,: 1.2.3.4) before sending it in an update.
• Only update when the IP address is different from the IP of the last update.

Unacceptable Client Behavior

• Send requests to or access anything other than /nic/update at the host members.dyndns.org.
• Reverse engineer web requests to our website to create or delete hostnames.
• Hardcode the IP address of any of the Dyn servers.
• Attempt to update after receiving the notfqdn, abuse, nohost, badagent, badauth, badsys return codes or repeated nochg return codes without user intervention.
• Perform DNS updates to determine whether the client IP needs to be updated.
• Access our web-based IP detection script (http://checkip.dyndns.com/) more than once every 10 minutes