Error updating group for lan to lan connection

The foundation of an Exchange Server 2010 Database Availability Group is Windows Failover Clustering.However unlike traditional Exchange server clusters which existed in an active/passive state, and in which the entire cluster group needed to failover to an alternative node together, with Exchange 2010 DAGs each mailbox database can failover (or switchover, if it is a deliberate move) to another DAG member independent of the other mailbox databases in the DAG.In those cases one of the other DAG members is able to bring their copy of the mailbox database online and then request missing emails be resent from the transport dumpster of Hub Transport servers within the site.In Exchange Server 2010 SP1 file mode replication is used to bring mailbox database copies into sync with each other (eg during the initial sync process when a new database copy is added).

Each server that is a member of the DAG can host either an active or passive copy of each of the three total mailbox databases.When the log buffer becomes full each DAG member then builds their own transaction log files from their own log buffer.Block mode replication has an advantage over file mode replication in failure scenarios, because each DAG member is completely up to date with all changes to the active database.How this applies to an Exchange Server 2010 DAG is that if you deploy a DAG with just two Mailbox servers as members (or any even number up to 16), then neither server is able to determine by majority vote whether it should make its own copy of a given mailbox database active.To achieve quorum for a DAG with an even number of member servers another server in the same site is designated as a File Share Witness for the cluster.