When Windows 2008 Essential Business Server is installed, your current DNS servers are stored in Active Directory.  EBS uses this data to configure the DNS settings on a server during a replacement mode install.  If you retire a DNS server between the original install and a replacement mode install the replacement mode install may fail at the Network Configuration step due to the fact that the server could not reach the decommissioned DNS server.  You will receive the following error message:

DNS record cannot be updated

The host (A) resource record for this server cannot be updated on DNS server <IP>. Wait a few minutes, and then click Retry.

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