How ACME HTTP-01 and DNS-01 Challenges Verify Domain Control Internally

The ACME protocol automates TLS certificate issuance by requiring clients to prove domain control before a certificate authority will issue a certificate. Two widely used verification methods are HTTP-01, which places a challenge response in the web server's HTTP path, and DNS-01, which inserts a cryptographically derived value as a DNS TXT record. Crucially, the certificate authority performs the validation independently rather than trusting the client's claim. This distinction matters in complex environments such as Kubernetes clusters or systems behind load balancers, where the component requesting the certificate may not directly control the infrastructure needed to complete the proof. Understanding these mechanisms requires examining the full chain of infrastructure dependencies, not just the certificate request itself.