Each domain has its own Domain Administration Server (DAS) with a unique port number. The Administration Console communicates with a specific DAS to administer the associated domain. Each Administration Console session allows you to configure and manage the specific domain.
The Domain Administration Server (DAS), is a specially-designated application server instance that hosts the administrative applications. The DAS authenticates the administrator, accepts requests from administration tools, and communicates with server instances in the domain to carry out the requests. The DAS is sometimes referred to as the admin server or default server. It is referred to as the default server because it is the only server instance that gets created on Sun Java System Application Server installation and can be used for deployments. The DAS is simply a server instance with additional administration capabilities.
Each Administration Console session allows you to configure and manage a single domain. If you created multiple domains, you must start an additional Administration Console session to manage the other domains. When specifying the URL for the Administration Console, be sure to use the port number of the DAS associated with the domain to be administered.