Consideration should be given to the amount of traffic that replication places on the WAN or a RAS dial-up line. In particular, avoid doing full synchronization across WAN links. Full synchronizations are required when first setting up a new PDC or bringing a new location online. Full synchronizations are also initiated when more than 2000 changes happen to user/groups within a short period of time (less than one hour). This is configurable by increasing the size of the change log. If you anticipate high change activity, you may wish to increase the value of this parameter.
An important part of administration is managing the amount of network traffic so that response time remains acceptable. When the PDC is located across a WAN or modem link, you can estimate the amount of traffic and time needed to replicate SAM changes to and from the PDC and then schedule this traffic to meet the needs of the site. The following chart helps you calculate the time needed for replication: