CCNA 2 EXAM 1-4 STUDY Guide copy 2

Router Bootup Sequence

1.- Executes the POST. 2.- The boot loader software. 3.- CPU initialization. 4.- flash memory. 5.- IOS image.

Frames are forwarded without any error checking. Cut-through switching reduces latency by forwarding frames as soon as the destination MAC address and the corresponding switch port are read from the MAC address table. This switching method does not perform any error checking and does not use buffers to support different Ethernet speeds.

10. Which characteristic describes cut-through switching? A. Error-free fragments are forwarded, so switching occurs with lower latency. B. Frames are forwarded without any error checking. C. Only outgoing frames are checked for errors. D. Buffering is used to support different Ethernet speeds.

A hub extends a collision domain, and a switch divides collision domains. Explanation: Hubs operate only at the physical layer, forwarding bits as wire signals out all ports, and extend the collision domain of a network. Switches forward frames at the data link layer and each switch port is a separate collision domain which creates more, but smaller, collision domains. Switches do not manage broadcast domains because broadcast frames are always forwarded out all active ports.

11. What is the significant difference between a hub and a Layer 2 LAN switch? A. A hub extends a collision domain, and a switch divides collision domains. B. A hub divides collision domains, and a switch divides broadcast domains. C. Each port of a hub is a collision domain, and each port of a switch is a broadcast domain. D. A hub forwards frames, and a switch forwards only packets.

ASIC (Application Specific Integrated Circuit)

used in Cisco switches to speed up switch operations so that the switch can have an increased number of ports without degrading switch performance.

store-and-forward switching

Which frame forwarding method receives the entire frame and performs a CRC check to detect errors before forwarding the frame?

Frame forwarding decisions are based on MAC address and port mappings in the CAM table. Explanation: Cut-through frame forwarding reads up to only the first 22 bytes of a frame, which excludes the frame check sequence and thus invalid frames may be forwarded. In addition to broadcast frames, frames with a destination MAC address that is not in the CAM are also flooded out all active ports. Unicast frames are not always forwarded. Received frames with a destination MAC address that is associated with the switch port on which it is received are not forwarded because the destination exists on the network segment connected to that port.

12. Which statement is correct about Ethernet switch frame forwarding decisions? A. Frame forwarding decisions are based on MAC address and port mappings in the CAM table. B. Cut-through frame forwarding ensures that invalid frames are always dropped. C. Only frames with a broadcast destination address are forwarded out all active switch ports. D. Unicast frames are always forwarded regardless of the destination MAC address.

They store frames received, thus preventing premature frame discarding when network congestion occurs. Explanation: Switches have large frame buffers that allow data waiting to be transmitted to be stored so the data will not be dropped. This feature is beneficial especially if the incoming traffic is from a faster port than the egress port used for transmitting.

13. How do switch buffers affect network performance? A. They provide error checking on the data received. B. They store frames received, thus preventing premature frame discarding when network congestion occurs. C. They provide extra memory for a particular port if autonegotiation of speed or duplex fails. D. They hold data temporarily when a collision occurs until normal data transmission resumes.

high port density Explanation: Switches that have a lot of ports (high port density) reduce the number of switches required. Meaning that you can handle the same traffic using fewer switches. This removes the need to send traffic between switches. Which reduces the chances of a collision.

14. Which switch characteristic helps keep traffic local and alleviates network congestion? A. high port density B. fast port speed C. large frame buffers D. fast internal switching

ASIC Explanation: Application-specific integrated circuits (ASICs) are used in Cisco switches to speed up switch operations so that the switch can have an increased number of ports without degrading switch performance.

15. Which switch component reduces the amount of packet handling time inside the switch? A. ASIC B. dual processors C. large buffer size D. store-and-forward RAM

Occurs first - The switch adds the source MAC address to the MAC address table. Occurs second - Because the destination is not known, the switch forwards the frame out all ports except the port through which the frame arrived. Explanation: The first step a switch does when processing a frame is to see if the source MAC address is in the MAC address table. If the address is not there, the switch adds it. The switch then examines the destination MAC address and compares it to the MAC address table. If the address is in the table, the switch forwards the frame out the corresponding port. If the address is missing from the table, the switch will forward the frame to all ports except the port through which the frame arrived.

16. Refer to the exhibit. A switch receives a Layer 2 frame that contains a source MAC address of 000b.a023.c501 and a destination MAC address of 0050.0fae.75aa. Place the switch steps in the order they occur. (Not all options are used.) Occurs first Occurs second a. The switch drops the frame. b. The switch adds the source MAC address to the MAC address table. c. The switch adds the destination MAC address to the MAC address table. d. Because the destination is not known, the switch forwards the frame out all ports except the port through which the frame arrived. e. Because the source MAC address is not known, the switch broadcasts the frame out all ports except the port through which the frame arrived.

source MAC address and incoming port number Explanation: A switch "learns" or builds the MAC address table based on the source MAC address as a frame comes into the switch. A switch forwards the frame onward based on the destination MAC address.

17. What information is added to the switch table from incoming frames? A. source MAC address and incoming port number B. destination MAC address and incoming port number C. source IP address and incoming port number D. destination IP address and incoming port number

store-and-forward Explanation: Two methods used by switches to transmit frames are store-and-forward and cut-through switching. The store-and-forward method performs error checking on the frame using the frame check sequence (FCS) value before sending the frame. In contrast, cut-through switching sends the frame as soon as the destination MAC address part of the header has been read and processed.

18. Which switching method ensures that the incoming frame is error-free before forwarding? A. cut-through B. FCS C. fragment free D. store-and-forward

8 Explanation: A router defines a broadcast boundary, so every link between two routers is a broadcast domain. In the exhibit, 4 links between routers make 4 broadcast domains. Also, each LAN that is connected to a router is a broadcast domain. The 4 LANs in the exhibit result in 4 more broadcast domains, so there are 8 broadcast domains in all.

19. Refer to the exhibit. How many broadcast domains are displayed? A. 1 B. 4 C. 8 D. 16 E. 55

when connecting a Cisco switch to a non-Cisco switch on links that should not be trunking (A,D) Explanation: Cisco best practice recommends disabling DTP on links where trunking is not intended and when a Cisco switch is connected to a non-Cisco switch. DTP is required for dynamic trunk negotiation.

20. Under which two occasions should an administrator disable DTP while managing a local area network? (Choose two.) A. when connecting a Cisco switch to a non-Cisco switch B. when a neighbor switch uses a DTP mode of dynamic auto C. when a neighbor switch uses a DTP mode of dynamic desirable D. on links that should not be trunking E. on links that should dynamically attempt trunking

It is a logical interface internal to the router The loopback interface is a logical interface internal to the router and is automatically placed in an UP state, as long as the router is functioning. It is not assigned to a physical port and can therefore never be connected to any other device. Multiple loopback interfaces can be enabled on a router. Section 1.4.6

6. What is a characteristic of an IPv4 loopback interface on a Cisco IOS router? A. The no shutdown command is required to place this interface in an UP state B. It is a logical interface internal to the router C. Only one loopback interface can be enabled on a router D. It is assigned to a physical port and can be connected to other devices

64 bytes The minimum Ethernet frame size is 64 bytes. Frames smaller than 64 bytes are considered collision fragments or runt frames and are discarded.

7. What is the minimum Ethernet frame size that will not be discarded by the receiver as a runt frame? A. 64 bytes B. 512 bytes C. 1024 bytes D. 1500 bytes

after POST execution Boot loader is executed in the 2nd step after POST execution

8. After which step of the switch bootup sequence is the boot loader executed? A. after CPU initialization B. after IOS localization C. after flash file system initialization D. after POST execution

an increase in the size of the broadcast domain Explanation: Adding a Layer 2 switch to a network increases the number of collision domains and increases the size of the broadcast domain.

9. Which impact does adding a Layer 2 switch have on a network? A. an increase in the number of dropped frames B. an increase in the size of the broadcast domain C. an increase in the number of network collisions D. an increase in the size of the collision domain

Dynamic Auto

Mode that passively waits for the neighbor to initiate trunking

The correct bootup sequence order is as follows: 1.- The switch loads and executes the POST. 2.- The switch loads the boot loader software. 3.- The boot loader performs low-level CPU initialization. 4.- The boot loader initializes the flash memory. 5.- The boot loader locates and loads the default IOS image.

Which router bootup sequence is correct? A. 1 - perform the POST and load the Cisco IOS software. 2 - locate and load the startup configuration file or enter setup mode. 3 - locate and load the bootstrap program B. 1.- The switch loads and executes the POST. 2.- The switch loads the boot loader software. 3.- The boot loader performs CPU initialization. 4.- The boot loader initializes the flash memory. 5.- The boot loader locates and loads the default IOS image. C. 1 - perform the POST and load the bootstrap program. 2 - locate and load the startup configuration file or enter setup mode. 3 - locate and load the Cisco IOS software D. 1 - perform the POST and load the startup configuration file. 2 - locate and load the bootstrap program. 3 - locate and load the Cisco IOS software

cut-through switching

a switching method that begins the forwarding process as soon as enough information has been received to make a forwarding decision. This switching method does not perform any error checking and does not use buffers to support different Ethernet speeds.