The Operations Master roles ( AKA FSMO pronounced FIZZMOE) are, by default, assigned to the first DC installed in an Active Directory environment.
Schema Master The Schema is the field structure of the AD Database in this context – The Schema master maintains that schema, in the case of Schema modifications – such as intalling Exchange, running adprep.exe/forestprep or a third party app that hooks itself into Active Directory (Cognos for example.) This role is unique to the forest. To view the Schema Master, you need to register the schmmgmt.dll file, and then add Schema Management to a mmc console. You can now right click and view the owner of this role (and change it if so desired.)