ns1b.sea1.discourse.cloud has no CNAME records.
Question and response
Question
dig ns1b.sea1.discourse.cloud. NS
Answer
The response has no answer records.
Authority
sea1.discourse.cloud. 1084 SOA ns1.discourse.cloud. hostmaster.discourse.org. 1772724234 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0