Ccna certification Practice Tests

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Appendix 

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  Answers to Practice Test Questions

 6.  B.  The End of Row (EoR) switch acts as a distribution switch for the Top of Rack (ToR) 

switches. A ToR switch will sit at the top of the rack and create an access method for 

all the equipment in the rack. Core switch is a term used for the aggregation and core 

switching functions of all the distribution switches. Virtual switch is a term used for 

switching inside of a hypervisor, in which software switching occurs.

 7.  A.  Switches allow for low latency because frames are forwarded with ASIC hardware-

based switching and have low cost. Software switching is only used by legacy bridges and 

virtual switches. Software switching can actually create latency. Using a switch lowers the 

cost (latency); it does not raise the cost.

 8.  A.  The replacement of hubs with switches increases collision domains and effectively 

increases bandwidth. The replacement of switches with hubs can decrease the number of 

collision domains, creating a much larger collision domain. The replacement of hubs with 

switches has no effect on broadcast domains. Broadcast domains would only be affected if 

a router was introduced.

 9.  D.  The switch learns MAC addresses based upon incoming ports and examination of 

the source MAC address. It will build a MAC address table for future lookups. It then 

determines forwarding interfaces based upon the destination MAC address contained 

in the frame. Forwarding of data is based upon physical addresses “burned” into the 

network interface card (NIC) called MAC addresses. Repeating electrical signals to all 

ports describes how a dumb hub would operate. MAC addresses are learned by the source 

MAC address on incoming frames to the switch, not the destination frames.

 10.  D.  A switch creates micro-segmentation, which in turns isolates traffic between two 

talking computers from other computers that are not part of the communications. This 

in turn increases bandwidth for the computers that are not part of the communications 

between the two talking computers. The creation of broadcast domains can only be 

achieved with the addition of VLANs and a router. The isolation of ARP messages can 

only be achieved by the creation of broadcast domains. Segmentation with a switch will 

create more collision domains, not fewer collision domains.

 11.  A.  Wire speed of a single port on a 48-port gigabit switch would be 1 Gb/s, or 1,000 

Mb/s. Theoretically, a port can transmit and receive simultaneously 1 Gb/s, but wire 

speed refers to a single direction. The wire speed of the entire switch (backplane) could 

be 48 Gb/s for a 48-port Gigabit Ethernet switch, although the backplane is usually 

oversubscribed on access layer switching.

 12.  C.  Each port on a switch creates its own collision domain. An increase in collision 

domains raises bandwidth since each port creates its own segment (micro-segmentation) 

and isolates possible collisions on other ports. All the ports on a hub will create a single 

collision domain, in which a signal from one computer can and will collide with another. 

Each port on the switch will not segment broadcasts unless each port is assigned a 

different VLAN, which is not common practice. Although each port on a switch will 

create a collision domain, it does not stop layer 2 broadcasts from being forwarded to all 

ports.

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Chapter 1: Network Fundamentals (Domain 1)