Every CDS server has a database called a clearinghouse in which it stores directory replicas. Directories are the units by which you distribute and replicate names throughout the namespace. You can have only one writable replica, called the master replica, in the cell. Other replicas of the cell are read-only.
If you are configuring a CDS server as a master CDS server, you must supply the LAN profile name for your host, if the cell uses multiple LANs.
If you are installing a CDS server as part of creating a new cell using CDS, the first CDS server in a cell is the master server (writable), also called the Initial Directory Server. All other CDS servers in the cell will be replica servers (read-only), or Additional Directory Servers.