Microsoft Windows Question:

Answer #1
The number of days before a deleted object is removed from the directory services. This assists in removing objects from replicated servers and preventing restores from reintroducing a deleted object. This value is in the Directory Service object in the configuration NIC

by default 2000 (60 days)

Answer #2
The Knowledge Consistency Checker (KCC) is a built-in process that runs on all domain controllers and creates the replication topology for the forest.