1. An apparatus comprising: at least one cache belonging to a first domain of a plurality of domains; at least one cache tag directory belonging to a hierarchy of cache tag directories, wherein the at least one cache tag directory includes at least one tag entry associated with at least one cache line from the at least one cache belonging to the first domain, wherein the at least one tag entry includes a domain state field, wherein the domain state field indicates whether a request from a core can be serviced in a domain of the plurality of domains.