As part of the Active Directory joining process, an automatic update of the related DNS server is attempted, by adding a new A record for the host being domain joined. If this is not possible; the Active Directory join still succeeds but a warning is heeded. This warning looks as follows and simply states that the domain join was successful but the dynamic DNS updating step after that had failed.
The cause for this behaviour is very often due to the fact that the DNS Server is set to not allow "Dynamic updates" (as seen in the image below), and/or the DNS server is intentionally statically managed.
To update the DNS server manually, simple add an A record for the Canaries IP. If the fully qualified domain name is corp.thinkst.com and the Canary's name is srv01, create an A record pointing srv01.corp.thinkst.com to the Canary IP.