Which of the following actions requires a reboot of an ESX Server?
Answer: Change the number of ports on switch
Explanation:
Most network activities can be performed without the reboot of the ESX Server. The exception is the modification of the number of ports on an existing virtual switch, which does require a reboot.
From….
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009103
Solution
You may experience this issue if the virtual switch has exceeded its number of configured VMkernel ports.
For example, if you have a single virtual switch (that is set to the default of 24 ports for VMware Infrastructure 3, 56 default ports in vSphere) with multiple port groups and virtual machines, but the output of the esxcfg-vswitch command shows that the virtual switch has 32 configured ports and 32 ports in use, the virtual switch has exceeded its number of configured ports.
Note: Virtual switches have overhead ports that do not show up in the output of the esxcfg-vswitch -l command. Each virtual network adapter in a virtual machine connected to the vswitch, each port group, and each NIC uplink uses one port. There are several more ports used by the vswitch that are hidden to the user.
There are several possible resolutions. To resolve this issue, either:
Increase the number of ports for the virtual switch and reboot the host for the changes to take effect.
I have the same idea.