IP-Directed Broadcast: Understanding its Statements | CCIE Data Center Exam

IP-Directed Broadcast Statements

Question

Which two statements about IP-directed broadcast are true? (Choose two.)

Answers

Explanations

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A. B. C. D.

AC.

IP-directed broadcast is a way of sending a broadcast message to all hosts in a specific IP subnet. The broadcast message is sent to a broadcast address, which is a specific IP address that is reserved for broadcasting to all hosts on the subnet. The use of IP-directed broadcast is common in some network protocols and applications, such as DHCP and ARP.

Here are the correct statements about IP-directed broadcast:

A. The destination address in the IP header of the packet is rewritten to the configured IP broadcast address for the subnet, and the packet is sent as a link-layer broadcast. This statement is true. When a host sends an IP-directed broadcast message, it sets the destination IP address to the broadcast address for the subnet. The switch then rewrites the destination MAC address to a broadcast MAC address, which is used to send the packet to all devices on the same subnet.

B. An IP-directed broadcast is an IP packet whose destination address is a valid broadcast address, and it originates from a node that is also part of the same subnet. This statement is also true. An IP-directed broadcast is a packet that is sent to the broadcast address of a specific subnet, and it originates from a node that is also part of the same subnet. The purpose of the IP-directed broadcast is to send a message to all devices on the subnet.

C. A switch that is not directly connected to its destination subnet forwards an IP-directed broadcast in the same way it forwards unicast IP packets destined to a host on that subnet. This statement is false. When a switch receives an IP-directed broadcast packet, it forwards the packet to all ports in the same VLAN, except for the port it received the packet from. If the switch is not directly connected to the destination subnet, it will not forward the packet.

D. All switches in the network forward an IP-directed broadcast in the same way they forward multicast IP packets. This statement is also false. While both multicast and IP-directed broadcast packets are sent to multiple devices, they are handled differently by switches. Multicast packets are sent to specific devices that have joined the multicast group, while IP-directed broadcast packets are sent to all devices on the subnet. As a result, switches handle these packets differently.

In summary, the correct statements about IP-directed broadcast are A and B.