We have an AD domain with one DC, one Terminal Server and one Exchange server. We wanted to add another DC to the group to allow for load sharing and have some redundancy. The additional DC was programed as per the first one and allowed to replicate with the first DC. As a test we removed the first DC from the domain and discovered that the Exchange server would not function with the new DC. Upon re-instating the first DC the Exchange server worked fine. Why would the introduction of the second DC cause the Exchange server to malfunction?