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I am new to the IT pro world ,can anyone shine some light on : What are the differences among Windows Network load balancing ,Hardware load balancing and Failover clustering?

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Windows network load balancing allows you to group multiple Windows servers into a pool. These servers will coordinate between themselves to hash up which hosts will serve specific requests. They rely upon the default forwarding behavior of Ethernet switches by replying to ARP requests with a MAC address that is never learned in the Ethernet forwarding table. This causes the traffic to be broadcast to all ports on the broadcast domain (see also: VLAN). This behavior allows all of the servers in the pool to receive the requests, and only the server that has been picked to serve the request will respond. You can limit the scope of the broadcast traffic with additional switch configuration, creative use of VLANs, or using an alternative supported multicast method.

Hardware load balancing generally refers to devices from companies like F5, Citrix, and A10. These are purpose built appliances that can perform significant amounts of logic with regard to the balancing decisions. They also include extensive health checking, weighting, acceleration, and high availability options. Many vendors now offer virtualized solutions that allow these functions to coexist in your virtualization environment.

Fail over clustering is commonly regarded as the ability to have 2 or more devices provide fault tolerance for each other. Primarily one device will handle the load, with the other device synchronizing state information about it's peer. This generally allows the backup or secondary device to take over the load in the event that the primary fails, or is no longer capable of handling the load.

While there are some significant networking considerations with regard to Windows network load balancing, the other two options do not generally have this behavior.

The discussion regarding the right option to pick takes a number of variables into consideration, and is best addressed on a case by case basis.

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