An administrator is configuring iSCSI for use with ESX 4. Which networking feature should be configured on the ESX host to improve iSCSI performance?

Answer: Jumbo Frames

Explanation:
+ EtherChannel is a Cisco feature that is used for switch-assisted load balancing. As such it is configured on the physical switch and is not an option that is configured on an ESX Host. Jumbo Frames can be used on a VMkernel port to allow for larger data payloads in fewer packets. Jumbo Frames can provide improved performance for IP-based storage and should be enabled when configuring an ESX Host for iSCSI.
+ NetQueue can be configured on an ESX Host to take advantage of multiple receive queues to improve receive-side networking performance. It is enabled by default and does not require configuration. Jumbo Frames can be used on a VMkernel port to allow for larger data payloads in fewer packets. Jumbo Frames can provide improved performance for IP-based storage and should be enabled when configuring an ESX Host for iSCSI.
+ PortFast is a Cisco feature that is used with Spanning Tree Protocol (STP). As such it is configured on the physical switch. Jumbo Frames can be used on a VMkernel port to allow for larger data payloads in fewer packets. Jumbo Frames can provide improved performance for IP-based storage and should be enabled when configuring an ESX Host for iSCSI.