The MX mechanism provides the ability to run multiple mail servers for a single domain, and allows administrators to specify an order in which they should be tried.
A more sophisticated approach is called "bursting", the administrator would specify a "peak rate limit", a lower "sustained rate limit", and a "credit limit".
An administrator may specify a certain level of disk space that a user may use before they receive a warning, and then deny access to the user once they hit their upper limit of space.
In dynamic groups, however, an administrator can specify search criteria.
Certain administrators can specify that this large disk is made of "data pools" (which are also virtual).
Windows Vista includes around 2400 Group Policy settings, which allow administrators to specify configuration for connected groups of computers, especially in a domain.
This process can be partially automated, where the administrator specifies the amount of disk space that may be used, and the database generates views according to actual usage.
Many routers allow the administrator to specify a particular, trusted DNS in place of the one suggested by an upstream node (e.g., the ISP).
During a manual installation, the administrator must specify configuration options.
Static routers require an administrator to manually set up and configure the routing table and to specify each route.