I am running the Bash script from the linked blog post on my local Raspberry Pi. Is your Lambda for pointing back to your home network? If so, that is awesome that you can do that using a remote service. If you don't mind sharing, how does it work?
Instead of using DynDNS my router at home is configured to hit an alternative url, the lambda. Every hour it pings my lambda with its current public IP. The lambda then uses my actual DNS provider’s API to update the record.
It seems the format of DynDNS HTTP posts is baked into a lot of products but obviously not every provider supports it