Explanation/Reference:
Explanation
The legacy adapter doesn't support bandwidth management (check screenshots below). and if we remove the legacy network adapter without adding a new one, what would we set with Set-VMNetworkAdapter? so the complete answer should be "Remove the legacy network adapter, then add a network adapter, and then run the Set
-VMNetworkAdapter cmdlet" but we're asked for what we should do FIRST.

(You'll see in the next screenshot that for a "Network adapter, bandwidth is managed here) http:// technet.microsoft.com/en-us/library/hh848457.aspx Set-VMNetworkAdapter Configures features of the virtual network adapter in a virtual machine or the management operating system.[...]
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MaximumBandwidth<Int64>Specifies the maximum bandwidth, in bits per second, for the virtual network adapter. The specified value is rounded to the nearest multple of eight. Specify zero to disable the feature.
Bandwidth management
Bandwidth management is a new feature in Windows Server 2012 R2 Hyper
-V that enables you to set both a minimum and maximum Mbps of throughput for any virtual network adapter. In Windows Server 2008 R2, you could configure a maximum bandwidth but not a minimum. Now you can configure both a minimum and a maximum for each virtual network adapter. You enable and configure bandwidth management on a virtual network adapter in the settings of a VM, as shown in Figure
3-12. For either the Minimum Bandwidth or Maximum Bandwidth
setting, configuring a value of 0 leaves that setting unrestricted.

You can also use the Set-VMNetworkAdapter to configure minimum and maximum bandwidth on a virtual network adapter. As an alternative to specifying a value for Mbps, you can use this cmdlet to specify a relative bandwidth weight between 0 and 100 relative to other virtual network adapters. To ensure that all virtual network adapters are given an equal minimum or maximum bandwidth, you can assign the same bandwidth weight to all adapters.