Let's Debug

Test result for oracle.com using http-01

No CAA record on oracle.com (wildcard=false) contains the issuance domain "letsencrypt.org". You must either add an additional record to include "letsencrypt.org" or remove every existing CAA record. A list of the CAA records are provided in the details.
oracle.com. 0 IN CAA 0 issue "symantec.com"
oracle.com. 0 IN CAA 0 issue "digicert.com"

Submitted Dec 6 02:29:04 2018. Sat in queue for 3ms. Completed in 3s. Show verbose information.