A WebLogic domain consists of an Administration Server together with any number of Managed Servers. The Administration Server allows you to configure all Managed Servers and resources within the domain. Every Managed Server needs to contact the Administration Server during startup so that it can obtain its configuration. For this reason, the Administration Server always should be started before any Managed Servers. The default startup script for a Managed Server takes the URL of the Administration Server as another command-line argument. For instance, you could start a Managed Server manually as follows:
startManagedWeblogic server-name http://localhost:7001
Even though the Administration Server is critical for administering all domain resources, it is possible in certain cases to start a Managed Server in the absence of the Administration Server.
Subsets of the Managed Servers within a domain may be placed in a cluster. Thus, a domain can consist of an Administration Server, any number of Managed Servers, and multiple clusters of these Managed Servers.
WebLogic allows you to create a domain that consists of a standalone Administration Server. Typically, this configuration will be used only in development environments. In this case, your applications will be deployed (and targeted) to the single WebLogic Server instance — effectively, you are hosting applications on the Administration Server.
In general, you should deploy your applications to Managed Servers ...