A Linux administrator is troubleshooting a new virtual machine (VM) that fails to obtain an IPv4 address via DHCP. Running sudo dhclient -v shows repeated DHCPDISCOVER messages being sent, but no DHCPOFFER replies are received. Other hosts on the same VLAN are obtaining addresses from the same DHCP server without issue. Which of the following is the most likely cause of the problem on this specific VM?
The DHCP scope has no available addresses to lease.
A host-based firewall on the VM is blocking inbound traffic on UDP port 68.
The hypervisor's virtual-switch security settings are preventing the VM's DHCP broadcasts from reaching the network.
Port security on the switch has shut down the port after exceeding its MAC address limit.
A host-based firewall on the VM that drops inbound UDP traffic to port 68 would prevent the DHCPOFFER (which is sent from the server's UDP 67 to the client's UDP 68) from reaching the DHCP client, resulting in the observed endless DHCPDISCOVER messages.
Why the other options are unlikely:
Virtual-switch security features that block forged transmits usually stop outbound frames rather than inbound offers; you would typically see no DHCPDISCOVER leaving the VM, not offers missing on return.
Switch port security that has disabled the port or exceeded the MAC limit would interrupt all traffic for the VM, not just the DHCP reply, and the interface would generally show a link-down or err-disabled condition.
An exhausted DHCP scope would affect all new clients on the VLAN, not a single VM; other devices would fail at the same time.
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CompTIA Linux+ XK0-006 (V8)
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