Chapter 2

Question 1

Repeater

Answer 1

receives bit signals sent by the NIC and other devices, strengthens them (in part by filtering out electrical noise and cleaning the signal), and then “repeats” them to other parts of the network

Question 2

hub

Answer 2

a multiport repeater

half-duplex, bandwidth shared

Question 3

network bandwidth

Answer 3

amount of data that can be transferred in an interval (usually measured in bits per second (bps))

Question 4

bandwidth sharing

Answer 4

when all computers connected to the hub must share the amount of bandwidth the hub provides

Question 5

uplink port

Answer 5

port used to connect two hubs together or connect a hub to a switch

Question 6

Switch

Answer 6

reads data in the message and determines which port the destination device is connected to, and forwards the message to only that port

full duplex, bandwidth dedicated to each port

Question 7

Steps of switch operation

Answer 7

1: The switch receives a frame
2: The switch reads the source and destination MAC addresses
3: The switch looks up the destination MAC address in its switching table
4: The switch forwards the frame to the port where the computer owning the MAC address is found
5: The switching table is updated with the source MAC address and port information

Question 8

Advantages of a switch over a hub

Answer 8

1: Each port gets dedicated bandwidth (instead of having to share bandwidth with all ports)
2: Can operate in full-duplex mode (can send and receive data simultaneously) while hubs can only operate in half-duplex mode (can send or receive data but not both at one time)

Question 9

Access point

Answer 9

Heart of a wireless network, all communication passes through it, most places use a wireless router which combines the functions of an AP, a switch, and a router

similar to a wired hub

receiving device sends an acknowledgement to indicate successful reception

Sometimes sending station must send a request to send (RTS) message and receive a clear to send (CTS) message before transmitting

Question 10

NIC/NIC driver tasks

Answer 10

provide a connection from computer to medium

Incoming messages: receives bit signals and assembles them into frames (verifies destination address , removes frame header and sends the resulting package to the network protocol)

Outgoing messages: receives packets from network protocol (creates frames by adding MAC addresses/error check)

Converts frames into bit signals suitable for the medium and then transmits them

Question 11

MAC address

Answer 11

consists of two 24 bit hexadecimal numbers (24 bit manufacturer ID called OUI and 24 bit serial number assigned by the manufacturer)

Question 12

NIC only permits inbound communications if the destination MAC address:

Answer 12

1: matches the NIC’s burned in address
2: is a broadcast address (ff-ff-ff-ff-ff-ff)
3: NIC is in a special mode called promiscuous

Question 13

unicast frame

Answer 13

when the destination MAC address matches the BIA of a NIC (intended for a single computer)

Question 14

broadcast frame

Answer 14

when the destination is the broadcast address (broadcast frames are intended to be processed by all computers on the network)

Question 15

Promiscuous mode

Answer 15

turns off the gatekeeper functions and enables the NIC to process all the frames it sees

Question 16

Things to consider when purchasing NIC

Answer 16

1: Select correct bus interface (bus connects the NIC to the motherboard)
2: NIC driver must be available for your OS

Question 17

Wireless NICs

Answer 17

must be chosen according to type of Access Point (AP) being used

Typical are Wireless-n, 802.11ac or 802.11 a/b/g/n

The letters a, b, g, n, and ac refer to the wireless networking standard the device supports

Question 18

Service set identifier (SSID)

Answer 18

the name assigned to the wireless network (used to connect wireless NICs to the network)

Question 19

Router

Answer 19

device that enables multiple LANs to communicate with each other by forwarding packets from one LAN to another

Question 20

Routers vs Switches

Answer 20

1: Routers connect LANs, switches connect computers
2: Routers work with logical (IP) addresses, switches work with physical (MAC) addresses
3: Routers work with packets, switches work with frames
4: Routers don’t forward broadcasts, switches do
5: Routers use routing tables, switches use switching tables

Question 21

broadcast domain

Answer 21

the devices to which broadcast frames are forwarded

Question 22

Default route

Answer 22

where to send a packet when the router doesn’t have an entry in its routing table

Question 23

Network unreachable

Answer 23

Message sent when the network can’t be found and there is no default route

Question 24

Default gateway

Answer 24

the IP address of the computer’s router (In a computer’s IP address configuration)