[citation needed][2] FSMO is a specialized domain controller (DC) set of tasks, used where standard data transfer and update methods are inadequate.
If the original FSMO holder experienced an unrecoverable failure, another DC can be made to "seize" the lost roles; however, there is a risk of data loss because of the lack of communications.
FSMO roles can be easily moved between DCs using the AD snap-ins to the MMC or using ntdsutil, which is a command line-based tool.
When a Forest is initially created, the first Domain Controller is a Global Catalog server by default.
If this is not the case, the Infrastructure Master role must not be housed on a domain controller which also houses a copy of the global catalog in a multi-domain forest, as the combination of these two roles on the same host will cause unexpected (and potentially damaging) behaviour in a multi-domain environment.