Server Replication

By default, PDCs check there SAM every 5 minutes (300 seconds) and update the BDCs. While this may seem quite frequent, it shouldn't really affect your LAN noticeably. However, it could slow you WAN traffic if your BDC and PDC are on different subnets.

You can edit the following registry entry on your PDC to increase the SAM update time:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
Edit the Pulse entry and increase the number of seconds to the desired amount.

Tank,

When a BDC polls the PDC to determine if any changes have occured the 'changes' are sent over the network not the entire SAM. So, unless your making modifications to your user accounts, group accounts, or machine accounts on a regular basis, the traffic caused by the RPCs being sent back and forth should be minimal.

If you check your Event Logs on your BDCs you'll see that when an update occurs it only makes "10 Changes made to SAM" or something to that effect. Its very small, don't worry about it.

Now, here's the issue. If your using a WAN connection to link up between your DCs and let's say you have MS Exchange running on that same link.. Your gonna have a problem. =) MS Exchange takes a min of 56K worth of bandwidthbecause of its RPC packets.

To answer your question... It causes traffic but not enough to worry about.

The answer above also has the correct information on modifying the reg to make the change to your DCs.

Marvin