<p sourcefile="exchange-ps/exchange/database-availability-groups/New-DatabaseAvailabilityGroup.md" sourcestartlinenumber="1">When creating a DAG, you need to specify a valid computer name for the DAG no longer than 15 characters that's unique within the Active Directory forest. In addition, each DAG is configured with a witness server and witness directory. The witness server and its directory are used only for quorum purposes where there's an even number of members in the DAG. You don't need to create the witness directory in advance. Exchange automatically creates and secures the directory for you on the witness server. The directory shouldn't be used for any purpose other than for the DAG witness server.
<p sourcefile="exchange-ps/exchange/database-availability-groups/New-DatabaseAvailabilityGroup.md" sourcestartlinenumber="3">The requirements for the witness server are as follows:
<ul sourcefile="exchange-ps/exchange/database-availability-groups/New-DatabaseAvailabilityGroup.md" sourcestartlinenumber="5">…