Video instructions and help with filling out and completing Are Form 8453 S Authenticate

Instructions and Help about Are Form 8453 S Authenticate

Welcome to the next free video in the Active Directory training course in the last video I looked at how to create sites and subnets in this video I will look at how these sites can be configured to replicate Active Directory traffic in an efficient way that matches the current state of your network first of all I will start with just the New York site in this particular case let's say the New York site has seven domain controllers in it if the client were to log into the network they would be authenticated by one of the domain controllers if the user then changed their password and logged off and logged on a second time they would be authenticated by a different domain controller for this reason you want replication within a site to happen quickly this type of replication is called intra site replication interest site replication is replication that happens between domain controllers in the one site you will be happy to know that Active Directory handles this kind of replication without any configuration it does this by connecting all the domain controllers in that site together in a ring you can see that the seven domain controllers are each connected to two other domain controllers this gives some redundancy and also reduces the number of connections required in sites with a large number of domain controllers in Windows Server 2003 and above intra site replication will start 15 seconds after a change has been made on a domain controller with such a small delay all domain controllers on this network will receive the change in less than a minute if the number of domain controllers on this network were increased to 8 the delay for a change to replicate to each domain controller starts to increase each domain controller will wait 15 seconds before sending replication data to the next domain controller to reduce the delay Active Directory will automatically create additional connections between some of the domain controllers when you have eight or more domain controllers in the one site this ensures that there are no more than three hops between one domain controller in the site and any other domain controller the extra connections ensure that changes in the site are propagated to each domain controller in less than a minute all these connections are created automatically in Active Directory inside the site so you never need to worry about configuring replication inside an individual site the next part of replication in Active Directory is between sites this kind of replication is called inter site replication in this example consider the link between New York and Washington in order for these two sites to replicate changes between each other there must be a site link connecting the two sites this is not created automatically and needs to be created by an administrator in this example New York has seven domain controllers in Washington has three domain controllers in order for replication to occur Active Directory will automatically pick a domain controller in each site to act as what is called a bridge head server the bridge head server in each site will replicate changes between the sites when a change is made on a domain controller it will be replicated to all other domain controllers in that site when the change reaches the bridge head server the bridge head server is responsible for replicating that change to the other bridge head server in the other site this system is a lot more efficient than individual domain controllers attempting to replicate changes to other sites Active Directory will automatically choose a domain controller in each site to act as a bridge head server for you if that domain controller is shut down or is no longer available a new domain controller will be chosen in some cases you may have a particular domain controller or domain controllers that you want to use as the bridge head server Active Directory allows you to select a domain controller or domain controllers to be the bridge head server for that site these are called preferred bridge head servers be warned however if you choose your own bridge head servers and these servers are not available no replication will occur between the two sites until one of those preferred bridge head servers comes back online once you have a site link configured you can configure some options on that site link the first option allows a schedule to be configured which will determine when replication will occur in some cases companies may configure this replication to happen after business hours the next setting allows a cost to be configured for that site link the cost is a numerical value that is applied to a site link telling Active Directory what priority these links should be used to better understand how costs work let's now consider what happens when the London office is added to the network the London office is connected to the New York office by a direct link in order for replication to occur a site link is created between London and New York the link between London and New York is unreliable and at times will go down for hours at a time for this reason another link is established between Washington and London this link is more reliable but is charged according to how much traffic is transferred over it and thus the company only wants to use this link when they have to in this example the London to New York site link and the New York to Washington site link are given a cost of 40 the site link between Washington and London is given a cost of 100 the cost of transferring data between sites is calculated by adding up the value of the site's links the route with the lowest cost will be used in order for data to go from Washington to London the lowest cost would