There are two basic types of WINS server failures:
In Figure 8.6, a failure of WINS-A or WINS-B would segment the distribution of WINS server services. Entries would no longer be replicated from WINS-C to WINS-D, and vice versa. Because the IP address and name would no longer match for updated clients, other clients would not be able to connect to the updated computers. Adding replication between WINS-B and WINS-C would improve the configuration for cases in which WINS-A fails. Adding replication between WINS-D and WINS-C would improve fault tolerance in a case where the WINS-B server fails.
Failure of one of the links between A, B, and C could be tolerated because the underlying router network would reroute the traffic. Failure of the link between B and D, however, would segment the communication between WINS servers and would make other network traffic impossible should there be an on-demand backup link between D and C. The WINS replication traffic would then be rerouted by the underlying router infrastructure.