CCNA 1 v6.0 Chapter 5: Ethernet: Check your Understanding Answers
1. At which layers of the OSI model does Ethernet function? (Choose two.)
- Application
- Presentation
- Session
- Transport
- Network
- Data link
- Physical
Explanation: Ethernet standards define both the data link layer protocols and the physical layer technologies.
2. Which standard specifies the Ethernet MAC sublayer functionality in a computer NIC?
- IEEE 802.2
- IEEE 802.3
- IEEE 802.5
- IEEE 802.11
- IEEE 802.15
Explanation: IEEE 802.3 specifies the Ethernet MAC sublayer functionality
3. What is the name given to the Ethernet MAC sublayer PDU?
- Segment
- Packet
- Frame
- Bit
Explanation: The MAC sublayer is part of the OSI data link layer. The frame is the data link layer PDU. Segments are associated with the transport layer, packets with the network layer, and bits with the physical layer.
4. What are the primary functions associated with data encapsulation at the Ethernet MAC sublayer? (Choose three.)
- Media recovery
- Frame deliminating
- Addressing
- Frame placement on the media
- Error detection
Explanation: The Ethernet MAC layer has two primary responsibilities: data encapsulation and media access control. Frame delimination, addressing, and error detection are part of data encapsulation. Media recovery and media access are part of CSMA/CD.
5. What happens when a data collision occurs on an Ethernet bus?
- The CRC value is used to repair the data frames.
- All devices stop transmitting and try again later.
- The device with the lower MAC address stops transmitting to give the device with the higher MAC address priority.
- The MAC sublayer prioritizes the frame with the lower MAC address.
Explanation: Ethernet uses CSMA/CD. When a collision is detected on the media, all devices stop transmitting to allow the collision to clear. After the collision has cleared, devices will again attempt to transmit.
6. What is true about the Ethernet MAC address? (Choose three.)
- A MAC address is 32 bits in length.
- The first 6 hexadecimal digits of a MAC address represent the OUI.
- The IEEE is responsible for assigning vendors a unique 6-byte code.
- The vendor is responsible for assigning the last 24 bits of the MAC address.
- The MAC address is also known as a burned-in address.
Explanation: The Ethernet MAC address is 48 bits in length with the first 3 bytes (6 hexadecimal digits) assigned by the IEEE. The vendor is responsible for assigning the last 24 bits in the address. Because this address was permanently configured on a device, it is also known as a burned-in address, or BIA.
7. What is the minimum and maximum Ethernet frame size as defined by IEEE 802.3?
- 64 bytes – 1518 bytes
- 64 bytes – 1522 byres
- 32 bytes – 1518 bytes
- 32 bytes – 1522 bytes
Explanation: The IEEE 802.3 standard defines a minimum frame size of 64 bytes and a maximum frame size of 1518 bytes. The IEEE 802.3ac standard released in 1998 extended the maximum size to 1522 bytes to allow the inclusion of an 802.1q VLAN tag in the Ethernet frame.
8. Which field in an Ethernet frame is used for error detection?
- Preamble
- Type
- Destination MAC Address
- Frame Check Sequence
Explanation: The Frame Check Sequence field is used to detect frames that might have been damaged in transit.
9. Which address is used as a destination address on a broadcast Ethernet frame?
- 0.0.0.0
- 255.255.255.255
- FF-FF-FF-FF-FF-FF
- 0C-FA-94-24-EF-00
Explanation: The broadcast MAC address is when all 48 bits are turned on and is represented by FF FFFF-FF-FF-FF.
10. Which address is a multicast MAC address?
- 0-07-E9-00-00-D4
- 01-00-5E-00-00-C8
- FF-FF-FF-FF-FF-FF
- FF-FF-FF-01-00-5E
Explanation: All multicast MAC addresses start with 01-00-5E.
11. What functions are provided by the ARP process? (Choose two.)
- Resolving IPv4 addresses to MAC addresses
- Resolving host names to MAC addresses
- Maintaining a table of mappings
- Resolving host names to IP addresses
- Maintaining a table of active IP addresses
Explanation: The ARP process resolves IPv4 address to MAC addresses and maintains a table of these mappings.
12. Which devices on a network will hear an ARP request?
- Only the device that has the IPv4 address that the request is looking for
- All devices in the L2 broadcast domain
- Only devices in the same collision domain
Explanation: RP requests are sent out with a broadcast MAC address. All devices in the L2 broadcast domain will hear the request and use the information it contains to update their ARP tables with information for the source device.
13. Fill in the blanks.
When ARP receives a request to map an IPv4 address to a MAC address, it first looks in its ____. If no entry is found, ARP will send out an ARP__.
ARP table or ARP cache, request
14. Fill in the blanks.
When a device receives an ARP request for a device with a different IP address, it will use the ____ information to update its ARP table and then it will ____ the packet.
source, drop
15. Fill in the blanks.
ARP ____ are sent to a broadcast MAC address, and ARP replies are sent to a ____ MAC address.
requests, unicast
16. Fill in the blanks.
When a switch receives a broadcast frame, it enters the source information in its ____ and then it ____ the frame to all ports except the one the frame was ____ on.
MAC address table, floods, received
17. Fill in the blanks.
The MAC address table is sometimes referred to as a ____ table because it is stored in ____ memory.
CAM, content addressable
18. What type of switching is used on current L2 switches to allow QoS?
- Store-and-forward
- Cut-through
- Fragment-free
- Fast-forward
Explanation: The sole forwarding method used on Cisco switches is store-and-forward. This is required where frame classification for traffic prioritization (QoS) is necessary.
19. What name is given to a physical port on a Layer 3 switch configured to act as a router port?
- Switch virtual interface
- Routed port
- Layer 3 EtherChannel
Explanation: Both an SVI and a Layer 3 EtherChannel port are logical interfaces. A routed port is a physical interface that has had Layer 2 functionality shut down in favor of Layer 3 functionality.
20. Fill in the blanks.
To configure a routed port, the interface must be put into Layer 3 mode by using the ____ interface configuration command. After this, the interface must be assigned an ____ address.
no switchport, IP