There are two types of LHS instances:

•Handle LHS
A Handle LHS hosts and provides resolution and administration of all Handles under a given prefix.

•Prefix LHS
A Prefix LHS hosts and provides resolution and administration of prefixes derived from a given prefix.

NOTE  Administration means creation, modification and deletion of the Handle Records. It requires administrator permissions. For more information, see Digital Object Identifier Resolution Protocol (DO-IRP) Specification.

The same LHS can provide both instances and can be responsible for any number of prefixes.

Both these LHSs operate with the same LHS software and are configured the same way.

Handle System service components are scalable and extensible to accommodate any large amount of service load. An LHS may consist of multiple service sites, each hosting a full replica of the Handles managed by the service. A site may be a primary site (it means that it can be used for administrative operations: to create, modify or delete Handle Records stored in its database) or a mirror site (no administrative operation is possible). Each service site may also consist of a cluster of computers working together, each with a particular subset of the Handles managed by the service. Having multiple service sites avoids any single point of failure and allows load balancing among these service sites. Using multiple servers at any service site distributes the service load into multiple server processes and allows less powerful computers to be utilized for the name service.