Some device manufacturers go a step further by only allowing their DDNS Service to be used by the devices they manufacture, and also eliminate the need for user names and passwords altogether. Generally this is accomplished by encrypting the device's MAC address using an cryptographic algorithm kept secret on both the DDNS server and within the device's firmware. The resulting decryption or decryption failure is used to secure or deny updates. Resources for the development of custom DDNS services are generally limited and involve a full software development cycle to design and field a secure and robust DDNS server.