Definition
Centralised Data ( Distributed System)
Centralised data is shared information stored at a single site through which access to that information must pass, rather than being partitioned or replicated across storage sites.
Even if several servers process requests, their accesses converge on the same store. Its storage capacity, I/O throughput and network connection can therefore limit size scalability.
Example
A Central Directory
A single online telephone directory stores every entry and handles every lookup and update at one site.
A hypothetical central DNS database containing all names would have the same limitation. The actual DNS avoids this single-store design through hierarchical distribution.