A virtual machine is unable to communicate with another virtual machine. Both virtual machines are connected to the Production port group on the same virtual switch and are running on the same host.
Which configuration is causing the inability of the virtual machines to communicate?
A. LLDP was enabled instead of CDP for the vSphere Distributed Switch.
B. Promiscuous Mode has been set to Allow on the Production port group.
C. The Production port group is configured to use a secondary PVLAN.
D. The speed and duplex settings for the virtual machine vmnics do not match.
Correct Answer: C
Explanation/Reference:
Explanation:
C: PVLANs are used to isolate ports within a given VLAN. For a PVLAN to work it must be configured in pairs, i.e. the primary VLAN(upstream) and the secondary VLAN(downstream). Secondary VLANS can be either isolated or community. In the case above the PVLAN was created as a secondary PVLAN and though on the same virtual switch it the two virtual machines cannot communicate with each other.
Incorrect Answers:
A: Both LLDP and CDP provide communication for exchanging information between networks. Thus it is not switch discovery issue that is causing the inability to communicate since the virtual machines are both connected on the same port group.
B: In vSphere you can set the security policy at the virtual switch or the port group level. One of the policies that it can be set to is promiscuous mode and this will only mean that if set to accept then the virtual adapter will receive only the frames passed through the switch, which in turn means that there will be communication.
D: The speed and duplex settings should not be an issue when both the virtual machines are located on the same switch and running on the same host.
References:
Kajamoideen M.R., VMWare ESXi Cookbook, Packt Publishing, Birmingham, 2014, p.98
Lowe, S. & Marshall, N., Mastering VMWare vSphere 5.5, Wiley and Sons, Indianapolis, 2014, p. 260-262