How to insert only new records [ not exists in destination ] & update existing records [exists in destination]

Hi All,

I have a scenario where am inserting / updating records into my destination table , which is completely different database server.

For ex: source table resides in DB Server1 & Destination table resides in DB Server2

Now, how to identify the new records which is not already present in destination & insert them into the DB 

and how to identify the existing records & update them.

R.Manjunathan