Which is service in your windows is responsible for replication of domain controller to another domain controller ?

File Replication service (FRS)

There are2 types of replication.

1> AD replication

2> Sysvol replication

AD replication uses RPC.

Sysvol uses DFS Replication (DFSR) service, if Domain is at2008 functional level and all DCs are WIndows Server2008 or higher OS version. If domain functional level is2003, Sysvol uses NT File Replication Service (NTFS).

Hope this helps.

dfs (distributed file services ) to replicate the content of sysvol folder 

File replication service is responsible for replication of sysvol folders and distributed file system between replica servers. it will replicate what ever changes which happends to sysvol  with replica servers. ntdutil command line tool is used to monitor  replication process.

In previous version ofWindows FRS (File Replication Service) was used to replicate the contents of the SYSVOL between domain controllers.

In Windows Server2008 domains you have the option to use DFS-R (Distributed File System Replication) to replicate the contents of Sysvol.

knowledge consistancy cheker(KCC)

Good question. Pls comment Irshad and Manoj answer if satisfactory

KCC is responsible for replication b/w DC with two way ring topology.

Below 2008 R2 Forest Function Level (FFL) --> "Windows File Replication Service".

After raising the FFL to at least2008 R2, then migrating your SYSVOL folder from "File Replication Service" to "Distributed File System Replication (DFS-R)" then another service will be found in the DC which is DFSR "Distributed File System Replication service"