Explanation/Reference:
Explanation:
Even though Network Load Balancing (NLB) hasn't changed significantly since Windows Server 2008 and isn't mentioned in this chapter, be sure to review the feature and its configurable options. For example, remember that in port rules for Network Load Balancing clusters, the Affinity setting determines how you want multiple connections from the same client handled by the NLB cluster. "Affinity: Single" redirects clients back to the same cluster host. "Affinity: Network" redirects clients from the local subnet to the cluster host. "Affinity: None" doesn't redirect multiple connections from the same client back to the same cluster host.
http://technet.microsoft.com/en-us/library/bb687542.aspx
Using NLB
Client Affinity
NLB offers three types of client affinity to minimize response time to clients and provide generic support for preserving session state. Each affinity specifies a different method for distributing client requests. In Application Center, the New Cluster Wizard sets affinity to Single by default. Later, you can use the cluster Properties dialog box to modify the affinity. The following table describes the three types of affinity.

No Affinity
With No affinity, NLB does not associate clients with a particular member. Every client request can be load balanced to any member. This affinity provides the best performance but might disrupt clients with established sessions, because subsequent requests might be load balanced to other members where the session information does not exist. Single Affinity In Single affinity, NLB associates clients with particular members by using the client's IP address. Thus, requests coming from the same client IP address always reach the same member. This affinity provides the best support for clients that use sessions on an intranet.
These clients cannot use No affinity because their sessions could be disrupted. Additionally, these clients cannot use Class C affinity because intranet clients typically have IP addresses within a narrow range. It is likely that this range is so narrow that all clients on an intranet have the same Class C address, which means that one member might process all of the requests while other members remain idle. Class C Affinity With Class C affinity, NLB associates clients with particular members by using the Class C portion of the client's IP address. Thus, clients coming from the same Class C address range always access the same member. This affinity provides the best performance for clusters serving the Internet. Bb687542.note (en- us, TechNet.10).gif Note It is not efficient for Internet clients to use Single affinity because, in Single affinity, NLB load balances each client by the client's entire IP address, which can span a broad range. By using Class C affinity, NLB associates clients with only the same Class C portion of the IP address with particular members. Therefore, you essentially reduce the range of IP addresses by which NLB load balances clients.