CCNA 1 - Module 5-7

Question 1

Binary vs. Decimal Numbering System

Answer 1

• Binary numbering system consists of 1s and 0s, called bits
• Decimal numbering system consists of digits 0 through 9

Question 2

a digit represents different values depending on the “position” the digit occupies in the sequence of numbers.

Answer 2

Binary Positional Notation

Question 3

• • s a base sixteen numbering system, using the digits 0 through 9 and letters A to F.
• It is easier to express a value as a single hexadecimal digit than as four binary bit.

Answer 3

Hexadecimal

Question 4

• are 128 bits in length. Every 4 bits is represented by a single hexadecimal digit. That makes the IPv6 address a total of 32 hexadecimal values.

Answer 4

IPv6 addresses

Question 5

How to convert hexadecimal numbers to decimal values

Answer 5

• Convert the hexadecimal number to 4-bit binary strings.
• Create 8-bit binary grouping starting from the rightmost position.
• Convert each 8-bit binary grouping into their equivalent decimal digit.

Question 6

How to convert decimal numbers to hexadecimal numbers

Answer 6

• Convert the decimal number to 8-bit binary strings.
• Divide the binary strings in groups of four starting from the rightmost position.
• Convert each four binary numbers into their equivalent hexadecimal digit.

Question 7

• is responsible for communications between end-device network interface cards.
• It allows upper layer protocols to access the physical layer media and encapsulates Layer 3 packets (IPv4 and IPv6) into Layer 2 Frames.
• It also performs error detection and rejects corrupts frames.

Answer 7

Data Link layer

Question 8

• The ___________ communicates between the networking software at the upper layers and the device hardware at the lower layers.

Answer 8

LLC sublayer

Question 9

• The _______ is responsible for data encapsulation and media access control.

Answer 9

MAC sublayer

Question 10

is the arrangement and relationship of the network devices and the interconnections between them.

Answer 10

topology of a network

Question 11

• – shows physical connections and how devices are interconnected.

Answer 11

Physical topology

Question 12

• – identifies the virtual connections between devices using device interfaces and IP addressing schemes

Answer 12

Logical topology

Question 13

• – the simplest and most common WAN topology. Consists of a permanent link between two endpoints.

Answer 13

Point-to-point

Question 14

• – similar to a star topology where a central site interconnects branch sites through point-to-point links

Answer 14

Hub and spoke

Question 15

• – provides high availability but requires every end system to be connected to every other end system

Answer 15

Mesh

Question 16

bus vs. ring

Answer 16

• Bus – All end systems chained together and terminated on each end.
• Ring – Each end system is connected to its respective neighbors to form a ring

Question 17

• Only allows one device to send or receive at a time on a shared medium.
• Used on WLANs and legacy bus topologies with Ethernet hubs.

Answer 17

Half-duplex communication

Question 18

• Allows both devices to simultaneously transmit and receive on a shared medium.
• Ethernet switches operate in full-duplex mode.

Answer 18

Full-duplex communication

Question 19

• All nodes operating in half-duplex, competing for use of the medium. Examples are:
• Carrier sense multiple access with collision detection (CSMA/CD) as used on legacy bus-topology Ethernet.
• Carrier sense multiple access with collision avoidance (CSMA/CA) as used on Wireless LANs

Answer 19

Contention-based access

Question 20

• Deterministic access where each node has its own time on the medium.
• Used on legacy networks such as Token Ring and ARCNET.

Answer 20

Controlled access

Question 21

• Used by legacy Ethernet LANs.
• Operates in half-duplex mode where only one device sends or receives at a time.
• Uses a collision detection process to govern when a device can send and what happens if multiple devices send at the same time

Answer 21

CSMA/CD

Question 22

• Used by IEEE 802.11 WLANs.
• Operates in half-duplex mode where only one device sends or receives at a time.
• Uses a collision avoidance process to govern when a device can send and what happens if multiple devices send at the same time.

Answer 22

CSMA/CA

Question 23

Address is also called __________

Answer 23

Physical address

Question 24

: (IEEE 802.2) Places information in the frame to identify which network layer protocol is used for the frame.

Answer 24

LLC Sublayer

Question 25

: (IEEE 802.3, 802.11, or 802.15) Responsible for data encapsulation and media access control, and provides data link layer addressing.

Answer 25

MAC Sublayer

Question 26

• This is the internal structure of the Ethernet frame.
• a. 64 bytes < Ethernet Frame Size < 1518 bytes
• b. 64 bytes > EFS == ‘collision fragment’ or ‘runt frame’ => automatically discarded
• c. 1500 bytes < EFS == ‘jumbo’ or ‘baby giant frame’

Answer 26

Ethernet frame

Question 27

• The Ethernet frame includes both a source and destination MAC address to deliver the Ethernet frame from Ethernet NIC to Ethernet NIC on the same LAN.

Answer 27

Ethernet Addressing

Question 28

• The Ethernet frame includes a frame check sequence (FCS) trailer used for error detection

Answer 28

Ethernet Error detection

Question 29

is received and processed by every device on the Ethernet LAN.

Answer 29

Ethernet broadcast frame

Question 30

is received and processed by a group of devices that belong to the same multicast group.

Answer 30

Ethernet multicast frame

Question 31

• • This frame forwarding method receives the entire frame and computes the CRC. If the CRC is valid, the switch looks up the destination address, which determines the outgoing interface. Then the frame is forwarded out of the correct port.

Answer 31

Store-and-forward switching

Question 32

• • This frame forwarding method forwards the frame before it is entirely received. At a minimum, the destination address of the frame must be read before the frame can be forwarded

Answer 32

Cut-through switching

Question 33

• Provides the lowest latency by forwarding packets immediately after reading the destination address.
• May relay packets with errors since it starts forwarding before the entire packet is received; faulty packets are discarded by the destination NIC.
• Represents a typical cut-through switching method.

Answer 33

Fast-forward switching

Question 34

• Balances the high latency and integrity of store-and-forward switching with the low latency and reduced integrity of fast-forward switching.
• Stores and checks the first 64 bytes of a frame for errors before forwarding, helping to detect collisions that typically occur in that segment.

Answer 34

Fragment-free switching

Question 35

• Frames are stored in queues that are linked to specific incoming and outgoing ports.
• A frame is transmitted to the outgoing port only when all the frames ahead in the queue have been successfully transmitted. It is possible for a single frame to delay the transmission of all the frames in memory because of a busy destination port.
• This delay occurs even if the other frames could be transmitted to open destination ports.

Answer 35

Port-based memory

Question 36

• Deposits all frames into a common memory buffer shared by all switch ports and the amount of buffer memory required by a port is dynamically allocated.
• The frames in the buffer are dynamically linked to the destination port enabling a packet to be received on one port and then transmitted on another port, without moving it to a different queue.
• Shared memory buffering also results in larger frames that can be transmitted with fewer dropped frames. This is important with asymmetric switching which allows for different data rates on different ports. Therefore, more bandwidth can be dedicated to certain ports (e.g., server port).

Answer 36

Shared memory

Question 37

full-duplex vs. half-duplex

Answer 37

• Full-duplex - Both ends of the connection can send and receive simultaneously.
  o Gigabit Ethernet ports only operate in full-duplex.
• **Half-duplex **- Only one end of the connection can send at a time.

Question 38

__________ feature is enabled by default on switches running Cisco IOS Release 12.2(18)SE or later. However, the feature could be disabled. For this reason, you should always use the correct cable type and not rely on the auto-MDIX feature
* can be re-enabled using the mdix auto interface configuration command

Answer 38

auto-MDIX