OBJ 2.3 X

Question 1

Port aggregation

Answer 1

o Reduces the volume of event data by consolidating duplicate event records and merging them into a single record

Question 2

Link Aggregation Control
Protocol (LACP)

Answer 2

▪ Achieves redundancy by having multiple links
between devices
▪ Load balancing occurs over multiple links
▪ Multiple links appear as single logical link

Question 3

Duplex

Answer 3

o Full duplex occurs when devices can both communicate at the same time
o Half duplex occurs when devices can either transmit or receive, but cannot do both at the same time

Question 4

Flow control

Answer 4

Prevents sender from sending data faster than receiver can get it

Question 5

Port mirroring

Answer 5

▪ Helpful to analyze packet flow over network
● Connect a network sniffer to a hub and it sees all
● But, switches require port monitoring for network analyzer to see all the traffic
▪ Port mirroring makes a copy of all traffic destined for a port and sends it
to another port

Question 6

Port security

Answer 6

Prevents unauthorized access to a switchport by identifying and limiting
the MAC addresses of the hosts that are allowed

Question 7

Auto-medium-dependent
interface crossover (MDI-X)

Answer 7

▪ An automated way to electronically simulate a crossover cable connector
even if using a straight-through patch cable
▪ If a switch doesn’t support MDIX, use a crossover cable to make them talk

Question 8

Power over Ethernet (PoE)/ Power over Ethernet plus (PoE+

Answer 8

▪ Supplies electrical power over Ethernet
● Requires CAT 5 or higher copper cable
● Provides up to 15.4 watts of power to device
● PoE+ provides up to 25.5 W of power to device

Question 9

Spanning Tree Protocol

Answer 9

o Permits redundant links between switches and prevents traffic loops
o Availability is measured in 9’s
▪ Five 9’s is 99.999% uptime and allows only 5 minutes down per year
o Shortest Path Bridging (SPB) is used for larger network environments instead

Question 10

Carrier-sense multiple access with collision detection (CSMA/CD)

Answer 10

Ethernet devices transmit based on a principle called carrier sense
multiple access/collision detect (CSMA/CD)

▪ Carrier sense
● Listen to the wire, verify it is not busy
▪ Multiple access
● All devices have access at any time
▪ Collision detect
● If two devices transmit at the same time, a collision occurs
● Back off, wait a random time, and try again

Question 11

Address Resolution Protocol (ARP)

Answer 11

▪ Used to display and modify entries in the Address Resolution Protocol (or
ARP) cache on a system
▪ An ARP entry in the cache will get deleted after 21,600 seconds (6 hours)
● arp -d