Any vendor selling Ethernet devices must register with the IEEE to ensure the
vendor is assigned a unique 24-bit code, which becomes the first 24 bits of the MAC address.
The last 24 bits of the MAC address are generated per hardware device. This helps to ensure
globally unique addresses for each Ethernet device.
14. What is the special value assigned to the first 24 bits of a multicast MAC address transporting an
Just as with multicast IP addresses, there is a special assigned value for multicast
MAC addresses. The first 24 bits are set in hex to: 01-00-5E. The remaining 6 hex digits are
derived from the lower 23 bits of the IP multicast.
15. What will a host on an Ethernet network do if it receives a frame with a unicast destination MAC
address that does not match its own MAC address?
A. It will forward the frame to the next host.
B. It will remove the frame from the media.
C. It will discard the frame.
D. It will strip off the data-link frame to check the destination IP address.
In an Ethernet network, each NIC in the network checks every arriving frame to see
if the destination MAC address in the frame matches its own MAC address. If there is no match,
the device discards the frame. If there is a match, the NIC passes the frame up to the next OSI
16. Which network device makes forwarding decisions based on the destination MAC address that is
contained in the frame?
Switches are the central connection point for a LAN and they maintain a MAC
address table. The MAC address table has a port number associated with a MAC address for
each particular device. The switch inspects a frame to look at the destination MAC address. The
switch then looks in its MAC address table and if that MAC address is found, the switch
forwards the data to the port that is associated with that particular MAC address.
17. Which network device has the primary function to send data to a specific destination based on the
information found in the MAC address table?
If a MAC address is found in the MAC address table, then data is sent to the
associated switch port. If the MAC address is not found in the MAC address table, the data is
sent to all switch ports that have devices attached to the same network.
18. Which function or operation is performed by the LLC sublayer?
A. It adds a header and trailer to a packet to form an OSI Layer 2 PDU.
The Ethernet LLC sublayer has the responsibility to handle communication
between the upper layers and the lower layers of the protocol stack. The LLC is implemented in
software and communicates with the upper layers of the application to transition the packet to the
lower layers for delivery.
19. What happens to runt frames received by a Cisco Ethernet switch?
A. The frame is sent to the default gateway.
B. The frame is returned to the originating network device.
C. The frame is broadcast to all other devices on the same network.
A switch builds a MAC address table by inspecting incoming Layer 2 frames and
recording the source MAC address found in the frame header. The discovered and recorded
MAC address is then associated with the port used to receive the frame.
21. What is auto-MDIX?
A. A feature that detects Ethernet cable type
B. A feature to automatically determine speed and duplex
A MAC address is composed of 6 bytes. The first 3 bytes are used for vendor
identification and the last 3 bytes must be assigned a unique value within the same OUI. MAC
addresses are implemented in hardware. A NIC needs a MAC address to communicate over the
LAN. The IEEE regulates the MAC addresses.
24. What are the two sizes (minimum and expected maximum) of an Ethernet frame? (Choose two.)
The minimum Ethernet frame is 64 bytes. The maximum expected Ethernet frame
is 1518 bytes. A network technician must know the minimum and expected maximum frame
size in order to recognize runt and jumbo frames.
25. Which two functions or operations are performed by the MAC sublayer? (Choose two.)
A. It performs the function of NIC driver software.
B. It adds a header and trailer to form an OSI Layer 2 PDU.
C. It is responsible for Media Access Control.
D. It adds control information to network protocol layer data.
E. It handles communication between upper and lower layers.
The MAC sublayer is the lower of the two data link sublayers and is closest to the
physical layer. The two primary functions of the MAC sublayer are to encapsulate the data from
the upper layer protocols and to control access to the media.