1. An apparatus comprising: a plurality of domains, wherein each domain comprises one or more cores, one or more caches, and a first-level cache tag directory, wherein the first-level cache tag directory includes a tag entry with a domain field associated with a cache line in one of the one or more caches, wherein the domain state field indicates whether a request from one of the one or more cores can be serviced by one of the one or more caches without accessing a second-level cache tag directory, the second-level cache tag directory associated with data in every cache in the plurality of domains and not belonging to the plurality of domains.