High-level introduction to DNS in the form of a comic.

How to setup DNS records to ensure that domains that do not send email cannot be used for spoofing.

Smart devices manufacturers often “hard-code” in a public DNS server, like Google’s 8.8.8.8, and their devices ignore whatever DNS server is assigned by the router. Fortunately, with a few simple firewall rules, you can intercept these hardcoded DNS queries and redirect them to your DNS resolver. These instructions are for pfSense, but can be adapted to other firewall/routers.

Good explanation of DNS for normies

Example script to use the livedns API from Gandi to dynamically update subdomains with dynamic IPs.