1. Which part of an Ethernet Frame uses a pad to increase the frame field to at least 64 bytes?
- A. EtherType
- B. Preamble
- C. Start of Frame Delimiter
- D. Data field
2. Which part of an Ethernet frame detects errors in the frame?
- A. Preamble
- B. Start of Frame Delimiter
- C. Frame Check Sequence
3. Which part of an Ethernet Frame describes the higher-layer protocol that is encapsulated?
- A. EtherType
- B. Preamble
- C. Start of Frame Delimiter
- D. Frame Check Sequence
4. Which part of an Ethernet Frame notifies the receiver to get ready for a new frame?
- A. Data field
- B. Preamble
- C. Start of Frame Delimiter
- D. Frame Check Sequence
5. Which data link sublayer controls the network interface through software drivers?
- A. MAC
- B. LLC
6. Which data link sublayer works with the upper layers to add application information for delivery of data to higher level protocols?
- A. MAC
- B. LLC
7. What is a function of the MAC sublayer? [Choose three.]
- A. Controls access to the media
- B. Checks for errors in received bits
- C. Uses CSMA/CD or CSMA/CA to support Ethernet technology
- D. Communicates between software at the upper layers and the device hardware at the lower layers
- E. Allows multiple Layer 3 protocols to use the same network interface and media
8. What are two methods for switching data between ports on a switch? [Choose two.]
- A. Cut-off switching
- B. Cut-through switching
- C. Store-and-forward switching
- D. Store-and-supply switching
- E. Store-and-restore switching
9. Which switching method can be implemented using fast-forward switching or fragment-free switching?
- A. Cut-off switching
- B. Cut-through switching
- C. Store-and-forward switching
- D. Store-and-restore switching
10. Which two types of memory buffering techniques are used by switches? [Choose two.]
- A. Long-term memory buffering
- B. Port-based memory buffering
- C. Shared memory buffering
- D. Short-term memory buffering
11. What feature automatically negotiates the best speed and duplex setting between interconnecting devices?
- A. Auto-MDIX
- B. Auto-MDIX
- C. Autonegotiation
- D. Autotune
12. Which two characteristics describe Ethernet technology? [Choose two.]
- A. It uses unique MAC addresses to ensure that data is sent to the appropriate destination.
- B. It is supported by IEEE 802.3 standards.
- C. It uses a ring topology.
- D. It typically uses an average of 16 Mbps for data transfer rates.
- E. It is supported by IEEE 802.5 standards.
The 802.3 Ethernet standard specifies that a network implement the CSMA/CD access control method. Each node on the network has a unique MAC address for communication purposes.
13. What statement describes a characteristic of MAC addresses?
- A. They are only routable within the private network.
- B. They are added as part of a Layer 3 PDU.
- C. They have a 32-bit binary value.
- D. They must be globally unique.
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 IPv4 packet?
- A. 01-5E-00
- B. 01-00-5E
- C. FF-00-5E
- D. FF-FF-FF
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 layer.
16. Which network device makes forwarding decisions based on the destination MAC address that is contained in the frame?
- A. Hub
- B. Repeater
- C. Switch
- D. Router
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?
- A. Modem
- B. Switch
- C. Hub
- D. Router
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.
- B. It communicates with upper protocol layers.
- C. It performs data encapsulation.
- D. It is responsible for media access control.
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.
- D. The frame is dropped.
In an attempt to conserve bandwidth and not forward useless frames, Ethernet devices drop frames that are considered to be runt [less than 64 bytes] or jumbo [greater than 1500 bytes] frames.
20. What addressing information is recorded by a switch to build its MAC address table?
- A. The source Layer 2 address of incoming frames
- B. The source Layer 3 address of outgoing packets
- C. The destination Layer 3 address of incoming packets
- D. The destination Layer 2 address of outgoing frames
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
- C. An Ethernet connector type
- D. A type of Cisco switch
Auto-MDIX is a feature that is enabled on the latest Cisco switches and that allows the switch to detect and use whatever type of cable is attached to a specific port.
22. What type of address is 01-00-5E-0A-00-02?
- A. An address that reaches every host inside a local subnet
- B. An address that reaches every host in the network
- C. An address that reaches a specific group of hosts
- D. An address that reaches one specific host
The multicast MAC address is a special value that begins with 01-00-5E in hexadecimal. It allows a source device to send a packet to a group of devices.
23. Which statement is true about MAC addresses?
- A. The ISO is responsible for MAC addresses regulations.
- B. MAC addresses are implemented by software.
- C. The first three bytes are used by the vendor assigned OUI.
- D. A NIC only needs a MAC address if connected to a WAN.
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.]
- A. 64 bytes
- B. 1024 bytes
- C. 1518 bytes
- D. 128 bytes
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.