Question 4
1 ?pts
What are two features of ARP? (Choose two.)
If no device responds to the ARP request, then the originating node will broadcast the data packet to all devices on the network segment.
If a device receiving an ARP request has the destination IPv4 ?address, it responds with an ARP reply.
If a host is ready to send a packet to a local destination device and it has the IP address but not the MAC address of the destination, it generates an ARP broadcast.
When a host is encapsulating a packet into a frame, it refers to the MAC address table to determine the mapping of IP addresses to MAC addresses.
An ARP request is sent to all devices on the Ethernet LAN and contains the IP address of the destination host and its multicast MAC address.
The correct answer and explanation is:
Correct Answer:
- If a device receiving an ARP request has the destination IPv4 address, it responds with an ARP reply.
- If a host is ready to send a packet to a local destination device and it has the IP address but not the MAC address of the destination, it generates an ARP broadcast.
Explanation:
Address Resolution Protocol (ARP) is a network protocol used to map an IPv4 address to a physical MAC address. ARP operates within a local network (typically Ethernet) and is crucial for the communication of devices that rely on IP addresses for routing but require MAC addresses to deliver packets across the local network.
- ARP Request and ARP Reply:
- When a device needs to send data to another device within the same network, it first needs the MAC address of the destination device. The sender knows the destination’s IPv4 address but not its MAC address.
- To find this MAC address, the sender generates an ARP request. This request is broadcast to all devices on the local network, asking: “Who has this IP address?”.
- If a device on the network has the IP address being queried, it will respond with an ARP reply, which contains its MAC address. The response is sent directly back to the requesting device. This way, the source device can now encapsulate the packet with the correct MAC address and send it to the destination device.
- ARP Broadcast:
- When a host intends to send a packet to a local destination device but does not have the MAC address corresponding to the destination’s IP address, it broadcasts an ARP request. This broadcast is sent to all devices on the local network.
- All devices receive the ARP request, but only the device with the matching IP address will respond. This ensures that the sender can resolve the destination’s MAC address without having to know it beforehand.
The remaining options describe scenarios that either involve misunderstandings of ARP behavior or relate to unrelated networking concepts, such as the use of multicast MAC addresses, which is not a part of standard ARP operation. ARP specifically uses broadcast for its requests and replies, not multicast.
These two key features—ARP requests and replies—ensure that devices can dynamically discover each other’s MAC addresses and communicate effectively in an Ethernet network.