During Microsoft Dynamics CRM Server 2011 Setup, you can select to install a server role individually, one of the three predefined group of server roles, or a full server installation that includes all roles. Server roles let you increase flexibility and scalability of the Microsoft Dynamics CRM deployment. Note that all server roles must be running and available on the network to provide a fully functioning Microsoft Dynamics CRM system.
Install server roles by running Microsoft Dynamics CRM Server Setup
Install server roles by running Microsoft Dynamics CRM Server 2011 at the command prompt
For more information see Use the Command Prompt to Install Microsoft Dynamics CRM.
Microsoft Dynamics CRM Server 2011 placement
For improved application performance, the computer or computers that run the Microsoft Dynamics CRM Server 2011 roles and the computer that is running SQL Server should be on the same LAN. This is because of the large amount of network traffic passing between the computers. This is also recommended with Active Directory where the computer or computers on which Microsoft Dynamics CRM Server 2011 and the Active Directory domain controller are running should be on the same LAN to guarantee efficient Active Directory access to Microsoft Dynamics CRM.