Today we take a break to review the mechanics of Active Directory replication:
We are referring to intrasite replication for the most often use cases of Active directory domain name-context item changes. Such AD replication takes place between DCs in pull operations, not pushes.
Each domain controller (DC)  stores three naming contexts (NC)  in its local copy of AD at the minimum. These are schema NC, Configuration NC, and AD Domain NC which corresponds to AD Data.  The last one is usually the one that frequently changes. There are two type of writes - an originating write and a replication write.  Since directory changes can be made from any active directory DC, any one DC can be the originating DC.  AD controls and manages the transmission of AD Data with replication metadata.
The first item of replication metadata is the USN which is the update sequence number and pertinent only locally at a DC to indicate a sequence number associated with the changes at that DC.
The other DCs keep track of these USN for each other. The other DCs are referred to by their GUIDs so that the information does not change when the DC is renamed or offline.
Since an originating change can be come a replicated change for the other DCs and perpetually propagated, the cycle is broken with the help of an indicator called the high watermark vector. This tells apart an originating change from a replicated change and also prevents repeated changes for the same entry.
#codingexercise
Given an array integer k, find the maximum of each and every contiguous subarray of size k
Yesterday we saw a simple but O(n^2) complexity for solving this exercise.
We could also make it linear by keeping track of a list of  candidates in sorted descending manner. As the window moves the numbers smaller than the current number are removed from the tail and the max element from the head is printed. The list keeps track of index only.
void PrintMax(List<int>nums, int k)
{
var sorted = new List<int>();
if ( k < nums.count() || k == 0 || nums.empty()) return;
int I;
for (int I =0; I < k; i++)
{
while (!sorted.empty() && nums[I] >= nums[sorted.Last()]))
      sorted.RemoveLast();
Sorted.InsertLast(I);
}
for (int I = k; I < n; i++)
{
Console.WriteLine(nums[sorted.first()]);
while (!sorted.empty() && sorted.frst() <= I - k)
      sorted.RemoveFirst();
while (!sorted.empty() && nums[I] >= nums[sorted.Last()])
      sorted.RemoveLast();
sorted.InsertLast(I);
}
Console.WriteLine(nums[sorted.first()]);
}