DevOps
DevOps Roadmap - https://roadmap.sh/devops
Linux Journey - https://linuxjourney.com/
Docker Docs - https://docs.docker.com/
All DNS record types - https://www.nslookup.io/learning/dns-record-types/
(Almost) Every infrastructure decision I endorse or regret after 4 years running infrastructure at a startup - https://cep.dev/