A host needs to send a packet to a device on a remote LAN but has no ARP cache mappings. How will it obtain the necessary destination MAC address?

A host needs to send a packet to a device on a remote LAN but has no ARP cache mappings. How will it obtain the necessary destination MAC address?

• A. It will perform a DNS query
• B. It will send an ARP request to the default gateway
• C. It will broadcast to all devices on the local segment
• D. It will initiate a TCP session

Answer: (B)

A host that needs to send a packet to a device on a remote LAN and has no ARP cache mappings will send an ARP request to the default gateway in order to obtain the necessary destination MAC address. When a host does not have an ARP entry for the destination IP address, it cannot directly send frames to that address since frames require the MAC address. In networking, the default gateway is typically set to handle traffic destined for addresses outside the local subnet. When the host recognizes that the destination device is on a different network, it sends an ARP request to the default gateway's IP address to ask for its MAC address. The default gateway serves as an intermediary, allowing communication between devices on different networks. Once it receives the ARP request, the gateway will reply with its MAC address, enabling the host to send packets to that gateway. This method is more efficient than broadcasting to all devices on the local segment, which would create unnecessary network traffic and is ineffective for reaching devices beyond the local network. Initiating a TCP session is also not applicable here since the host first needs the correct MAC address to frame its packet and send it to the destination. A DNS query is not relevant to obtaining a MAC address, as DNS is used

A host that needs to send a packet to a device on a remote LAN and has no ARP cache mappings will send an ARP request to the default gateway in order to obtain the necessary destination MAC address. When a host does not have an ARP entry for the destination IP address, it cannot directly send frames to that address since frames require the MAC address.

In networking, the default gateway is typically set to handle traffic destined for addresses outside the local subnet. When the host recognizes that the destination device is on a different network, it sends an ARP request to the default gateway's IP address to ask for its MAC address. The default gateway serves as an intermediary, allowing communication between devices on different networks. Once it receives the ARP request, the gateway will reply with its MAC address, enabling the host to send packets to that gateway.

This method is more efficient than broadcasting to all devices on the local segment, which would create unnecessary network traffic and is ineffective for reaching devices beyond the local network. Initiating a TCP session is also not applicable here since the host first needs the correct MAC address to frame its packet and send it to the destination. A DNS query is not relevant to obtaining a MAC address, as DNS is used