Hello @Vishu Thank you for posting your question on Microsoft Q&A platform. Sorry for the delayed response.
From the details provided, I understand that you want to change the DNS for the replicated VM. In this case, I would suggest associating your DNS with the virtual network. This configuration should help accomplish your requirement.
There is a similar discussion here - https://learn.microsoft.com/en-us/answers/questions/950245/azure-site-recovery-and-automatic-dns-resolution might be helpful.
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