Thanks for posting in Q&A platform.
Before we go further, I would like to confirm the following information with you:
A. May I know how the DNS tag was configured in IPv4 Properties of DHCP server? Was Always dynamically update DNS records selected?
If yes, may I know have you configured credential for DNS dynamic update on DHCP server? You can check for it on Advanced tab in IPv4 Properties.
B. Meanwhile, was DHCP failover relationship configured?
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