Hi Aman,
After you add your custom domain name to Azure AD, you must return to your domain registrar and add the Azure AD DNS information from your copied TXT file. Creating this TXT record for your domain verifies ownership of your domain name.
Go back to your domain registrar and create a new TXT record for your domain based on your copied DNS information. Set the time to live (TTL) to 3600 seconds (60 minutes), and then save the record. After you register your custom domain name, make sure it's valid in Azure AD. The propagation from your domain registrar to Azure AD can be instantaneous or it can take a few days, depending on your domain registrar.
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