What are two functions of MAC addresses in a LAN? (Choose two.)

to allow the transfer of frames from source to destination
to determine which host has priority to transfer data
to indicate the best path between separate networks
to associate with a specific network IP address
to uniquely identify a node on a network

To allow the transfer of frames from source to destination:

Explanation: MAC addresses are embedded in the frame headers of data packets in a LAN. When a frame is sent, it includes both the source and destination MAC addresses. Switches within the LAN use these MAC addresses to forward the frame to the correct port, ensuring it reaches the intended device.
Importance: This function is crucial for intra-network communication, enabling devices to send and receive data accurately within the same local network.

To determine which host has priority to transfer data:

Explanation: This option refers to Quality of Service (QoS) mechanisms that prioritize certain types of traffic over others. However, QoS typically uses other identifiers like IP addresses or VLAN tags rather than MAC addresses for prioritization.
Relevance: While QoS can influence data transfer priority, it is not a primary function of MAC addresses.

To indicate the best path between separate networks:

Explanation: Determining the best path between networks is a function of routing protocols, such as OSPF, EIGRP, and BGP. These protocols use IP addresses and other metrics to find optimal paths for data to travel across different networks.
Relevance: MAC addresses operate at the data link layer and do not play a role in path determination across networks, which occurs at the network layer.

To associate with a specific network IP address:

Explanation: The Address Resolution Protocol (ARP) associates MAC addresses with IP addresses. When a device knows the IP address it wants to communicate with but not the MAC address, it uses ARP to find the corresponding MAC address.
Importance: This function is important for ensuring that IP packets can be encapsulated in frames with the correct MAC address for delivery within a LAN.

To uniquely identify a node on a network:

Explanation: Each device on a network has a unique MAC address assigned by the manufacturer, which helps to distinguish it from other devices. This unique identifier ensures that frames can be delivered accurately to the intended device.
Importance: This uniqueness is essential for network communication, preventing address conflicts and ensuring that data is directed to the correct hardware.

Summary

The correct functions of MAC addresses in a LAN are:

To allow the transfer of frames from source to destination.
To uniquely identify a node on a network.

The other options involve mechanisms and protocols that operate at different layers or use different methods, rather than being direct functions of MAC addresses.