Chapter 6-8

Front 1

At which layers do wireless networks operate?

Back 1

Physical/Data Link

Front 2

Which frequency range is considered the golden zone?

Back 2

500 Mhz to 10 GHz

Front 3

Antennae that focus signals in a narrow range are called _________.

Back 3

Directional

Front 4

Antennae that transmit signals in all directions are called __________.

Back 4

Omnidirectional

Front 5

Which type of antenna, assuming the same power output, allows signals to be sent over longer distances?

Back 5

Directional

Front 6

Write the inverse square law for wireless signal attenuation

Back 6

S2 = S1 (R1/R2)^2

Front 7

The wireless signal strength 10 feet from an access point is 75 mW. How strong is the signal 100 feet from the access point?

Back 7

.75 mW

Front 8

Which wireless propagation problem is described as the loss of signal strength due to interaction with air molecules, plants, and other things it passes through?

Back 8

Absorbative attenuation

Front 9

Which wireless propagation problem is described as the loss of signal strength due to the spreading of the signal as distance from the transmitter increases?

Back 9

Inverse square law attenuation

Front 10

Which wireless propagation problem is described as loss of signal strength due to the blocking of large or dense objects between transmitter and receiver?

Back 10

Shadow zones

Front 11

Which wireless propagation problem is described by the receiver receiving the same signal from direct and one or more reflected paths?

Back 11

Multipath interference

Front 12

Which wireless propagation problem is described by energy from other electrical devices that disrupt transmitted signals?

Back 12

Electro-magnetic interference

Front 13

What is the nomenclature for wireless LAN standards?

Back 13

802.11

Front 14

What is the primary difference between a wireless access point and a wireless router?

Back 14

Access point extends the WLAN; wireless router contains the five functions, of which one is WLAN access.

Front 15

What is the maximum range of a typical wireless LAN?

Back 15

30-100 meters

Front 16

Write the Shannon Equation

Back 16

C=B[log(1+S/N)]

Front 17

In the Shannon Equation, what does the variable C describe?

Back 17

Maximum possible bandwidth

Front 18

In the Shannon Equation, what does the variable B describe?

Back 18

Channel bandwidth

Front 19

In the Shannon Equation, what does the variable S/N describe?

Back 19

Signal to noise ratio

Front 20

True/False: The 802.11 protocols operate in unlicensed radio bands?

Back 20

True

Front 21

How many channels in the 2.4 GHz radio band are non-overlapping?

Back 21

3

Front 22

List the non-overlapping 2.4 radio channels

Back 22

1,6,11

Front 23

Which wireless propagation problems are greater in the 5 GHz radio band?

Back 23

Shadow zones & Inverse square law attenuation

Front 24

The maximum number of non-overlapping channels in the 5 GHz radio band is ________.

Back 24

24

Front 25

How wide are 802.11 channels usually?

Back 25

20 MHz

Front 26

Which wireless propagation problem is mitigated using spread-spectrum signal transmission?

Back 26

Multipath interference

Front 27

What is the dominant spread spectrum transmission method?

Back 27

OFDM

Front 28

Between a wireless laptop PC and an access point, what type of message is transmitted?

Back 28

802.11 frame

Front 29

Between a wireless access point and its wired Ethernet switch, what type of message is transmitted?

Back 29

802.3 Frame

Front 30

In wireless LANs, the handing off of a mobile host between access points is called _______.

Back 30

Roaming

Front 31

All wireless hosts and the access point that serves them transmit on the same channel. Why does this cause throughput to fall as the number of wireless hosts increase?

Back 31

As more hosts join an access points, the time between transmission to avoid collisions will increase, resulting in decreased throughput.

Front 32

What protocol is used to ensure that multiple wireless hosts on the same wireless LAN do not transmit simutaneously?

Back 32

CSMA/CA + Ack

Front 33

Is the CSMA/CA + Ack protocol reliable?

Back 33

Yes

Front 34

is the protocol CSMA/CA + Ack required for reasonably good operation of a wireless access point?

Back 34

Yes

Front 35

Which wireless protocols uses OFDM?

Back 35

802.11g & n

Front 36

What is the rated speed of 802.11g

Back 36

54 Mbps

Front 37

What is the rated speed of 802.11n

Back 37

300 Mbps

Front 38

Which two reasons does 802.11n provide faster speeds than 802.11g?

Back 38

802.11n uses MIMO and has a greater channel bandwidth

Front 39

Using two different antennas to send two or more simultaneous radio signals in the same channel to increase wireless speeds significantly is called?

Back 39

MIMO

Front 40

Which method brings both higher speeds and longer transmission distances to 802.11 wireless communication?

Back 40

MIMO

Front 41

People that search for unprotected worming access points are called?

Back 41

War drivers

Front 42

Unauthorized access points set up by employees are called ________ access points.

Back 42

Rogue

Front 43

People that park outside a company's premises and intercept a firm's data transmissions are called?

Back 43

Drive-by hackers

Front 44

The protection provided by 802.11 core security standards extends between which two components of the WLAN?

Back 44

Wireless host and access point

Front 45

Which of the following provides the weakest security to wireless networks?

Back 45

WEP

Front 46

The 802.11i security protocol is also known as _________.

Back 46

WPA2

Front 47

Which wireless security provides the strongest security to wireless networks?

Back 47

WPA2

Front 48

The encryption method used by 802.11i is known as __________.

Back 48

AES-CCMP

Front 49

What are the two modes of 802.11i operation?

Back 49

802.1x (enterprise) mode and PSK (Personal) mode

Front 50

The enterprise mode of 802.11i is also known as _________?

Back 50

802.1x

Front 51

What is the name of the protocol used by 802.1x central authentication server?

Back 51

Radius

Front 52

Why are extensible authentication protocols required for wireless access points but not for wired LAN connections?

Back 52

In wireless LANs, it is difficult for an imposter to tap into an access line and break into a network. With access points, it is much easier for transmissions to be intercepted and mimicked.

Front 53

What is the most common wireless EAP protocol (because it is favored by Microsoft)?

Back 53

PEAP

Front 54

In 802.11i, personal mode equates to _________.

Back 54

Pre-shared key (PSK)

Front 55

Describe why 802.11i PSK modes is different than WEP.

Back 55

In WEP, all wireless users on an access point share the same key during all wireless communications. Hackers can exploit the same shared key by capturing large amounts of traffic and deciphering the key through commonalities in the transmitted data. In WPA2 PSK mode, only the initial authentication uses the shared key. After initial authentication, the access point sends the user an unshared session key that is unique to each user. Also, during ongoing communications, the session key changes often, making capturing of data for cryptographic analysis very difficult.

Front 56

What is the main potential weakness of 802.11i PSK mode?

Back 56

If the pre-shared key is short (less than 20 characters), hackers can use a brute-force attack to gain initial access to the wireless network.

Front 57

Which threat is described as a malicious computer configured to act like a real access point?

Back 57

Evil twin

Front 58

Which method can be used to secure host-to-host communication from a man-in-the-middle attack?

Back 58

VPNs

Front 59

Which of the following provide end-to-end protection between a client operating anywhere on the Internet and a properly configured application server?

Back 59

VPNs

Front 60

Describe how a VPN protects against Evil Twins?

Back 60

While Evil Twin access points can read all wireless transmissions from a wireless host, all communication between the client and server will be encrypted using a pre-shared key; this pre-shared key is embedded in the wireless host and not transmitted, therefore the Evil Twin can not copy the key to decrypt messages.

Front 61

Name the three steps in access point placement.

Back 61

1) Initial planning, 2) initial site survey and installation, 3) ongoing site security.

Front 62

Which protocol is designed for use in Personal Area Networks (PANs)?

Back 62

Bluetooth

Front 63

Which of the protocol has a designed service range of up to 10 meters?

Back 63

Bluetooth

Front 64

Which wireless protocol operate in the 2.4 GHz service band?

Back 64

Bluetooth & 802.11i

Front 65

What two characteristics differ between classic, high-speed, and low-energy Bluetooth versions?

Back 65

Transmission speed and power requirements

Front 66

The type of control used by Bluetooth is called __________.

Back 66

Master-slave control

Front 67

True/False: A bluetooth master can have many slaves.

Back 67

True

Front 68

Bluetooth specifies transmissions at which network layers?

Back 68

Physical and data link

Front 69

What is the Bluetooth handshake called?

Back 69

Peering

Front 70

How wide are Bluetooth channels?

Back 70

1 MHz

Front 71

Bluetooth transmissions switch channels every 1600 microseconds to improve communication reliability and decrease interference with 802.11 transmissions. The protocol that manages this type of transmission is called ________.

Back 71

Frequency hopping spread spectrum

Front 72

How are passive RFID tags powered?

Back 72

A powered device transmits sufficient power, at 13.56 kpbs operation frequency, which enables the RFID to generate a reply.

Front 73

What is the main difference between active and passive RFID tags?

Back 73

Active RFID tags contain batteries, passive do not.

Front 74

What is the main concern for NFC, and RFID tags in particular?

Back 74

Inadvertent reading of RFID information (such as for credit cards) by bad guys.

Front 75

What are the three parts of the IPv4 hierarchical IP address?

Back 75

Network part, subnet part, host part.

Front 76

What is the maximum number of bits in an IPv4 IP address?

Back 76

32

Front 77

What part of the IPv4 IP address identifies smaller units of a host's network?

Back 77

subnet part

Front 78

What part of the IPv4 IP address identifies the host's network on the internet?

Back 78

Network part

Front 79

In the IP address 10.11.13.13, what is the network part?

Back 79

It is impossible to know without having the subnet mask available.

Front 80

What type of router connects different networks?

Back 80

Border routers

Front 81

What type of router connects different subnets within a firm?

Back 81

Internal routers

Front 82

How many bits are in a subnet mask?

Back 82

32

Front 83

What is the purpose of the network/subnet mask?

Back 83

To allow routers to determine the network part of an IP address for proper routing

Front 84

What is the difference between a subnet mask and a network mask?

Back 84

In a network mask, the initial 1's pf the mask identify the network part of the address. In a subnet mask, the initial 1's of the mask identify the network and subnet parts of the address.

Front 85

What do switches use in determining switching decisions?

Back 85

Switching tables

Front 86

What do routers use in making routing decisions?

Back 86

Routing tables

Front 87

What addresses do switches use in making switching decisions?

Back 87

Destination MAC addresses

Front 88

What addresses do switches use in making routing decisions?

Back 88

Destination IP addresses

Front 89

Why is Ethernet switching so much more efficient than IP routing on the Internet?

Back 89

First, Ethernet switches are configured in a hierarchical topology with only one possible active path for a frame to transit inside a local network. Second, Ethernet switching tables contain rows that have each unique MAC address on the row; once the table reaches the row with the matching MAC address, it sends the frame out that respective port of the switch. In contrast, the Internet is a mesh network topology with many possible paths for an IP packet to take in its transit. Routers may have many rows in their routing tables that match a portion of the destination IP address; each row of a routing table must be examined for every packet routed. Thus, routers not only have to sort through many more rows of its routing table, but then has to execute a decision based upon one or more metrics.

Front 90

What are the three steps of a routing decision?

Back 90

Step 1, find all matching rows. Step 2, find the best-match row. Step 3, send the packet back out.

Front 91

What is the purpose of the default row in a routing table?

Back 91

The default row in a routing table is the last row in a routing table. Its purpose is to provide a match to every IP address so that the router has at least one choice in deciding where to route a packet.

Front 92

What is the longest match rule?

Back 92

When determining which row of a routing table to follow, the router chooses the row that has the longest mask possible, as this is the row that gets the packet closet to its destination.

Front 93

How do routers decide which row/route to choose if two or more rows have the same match length?

Back 93

In case of a tie for longest match, the tie-breaker is to use the metric column, which describes the goodness of a route. Lower cost in the metric column is better.

Front 94

What are router ports called?

Back 94

Interfaces

Front 95

When routing between subnets, what must be designed in the routing table?

Back 95

The net-hop router

Front 96

What is used when a router uses a previous decision for routing a packet instead of going through the 3-step routing decision process?

Back 96

Decision cache

Front 97

An arriving packet has the destination IP address of 128.171.180.13. Row 86 of the routing table has the destination value of 182.171.160.0 with a mask of 255.255.224.0. Does this row match the destination IP address? Explain.

Back 97

When examining masks that do not break at the natural 8 bit boundary, focus on the mask that follows the last .255. In this case, the first two octets have full .255 masks; the third octet is .224, so we focus on that octet. Applying the mask to the destination IP address, we get 128.171 and then need to calculate the impact of the mask: the binary representation of 180 = 1 0 1 1 0 1 0 0; the binary representation of 224 = 1 1 1 0 0 0 0 0; the result of masking = 1 0 1 0 0 0 0 0 = 160; Therefore, the resulting IP address for row 86 = 128.171.160.0. This shows that row 86 is a match. masks that do not break at the natural 8 bit boundary, focus on the mask that follows the last .255. In this case, the first two octets have full .255 masks; the third octet is .224, so we focus on that octet. Applying the mask to the destination IP address, we get 128.171 and then need to calculate the impact of the mask:

Front 98

A router determines the path for a packet to reach either a next-hop router or its final destination, but does not know how to forward the packet at the layer-2 frame level. How does a router determine a host s data link layer address?

Back 98

Routers use the Address Resolution Protocol (ARP)

Front 99

Explain the ARP process.

Back 99

1) Router creates an ARP request message and broadcasts the ARP packet to all hosts on the subnet. 2) Every host on the subnet examines the ARP packet and compares to its own IP address. The host has a matching IP address sends an ARP response message that includes its 48 bit MAC address. 3) The router logs the MAC address for that IP address and forwards the IP packet inside of a frame

Front 100

What is it called when routers save time by saving previous ARP responses?

Back 100

ARP caching

Front 101

In which layer does the ARP protocol belong?

Back 101

Internet

Front 102

What is the purpose of the TTL field in an IPv4 packet?

Back 102

To prevent misaddressed packets from circulating endlessly on the internet, routers decrease the Time-To-Live field of an IP packet by one each time it forwards the packet. When the TTL=0, the receiving router will discard the packet.

Front 103

What is the purpose of the Protocol field in an IPv4 packet?

Back 103

The protocol field value designates which process should receive the date field. ICMP = 1, TCP = 6, UDP=14/

Front 104

What three IPv4 packet fields are associated with IP-Layer fragmentation?

Back 104

Indentification, flags, Fragment offset

Front 105

What is the first field in an IPv4 packet, how long is it (in bits), and what is its value (in binary)?

Back 105

Version, 4 bits, 0100

Front 106

Which IPv4 packet field can be used for marking priority and other service parameters?`

Back 106

Diff-serv

Front 107

What are the first four fields in a TCP segment, and how long is each?

Back 107

Source port (16 bits), Destination port (16 bits), sequence number (32 bits), Acknowledgement number (32 bits)

Front 108

What are the six TCP flag bits?

Back 108

Urgent, FIN, Reset, Ack, Push, Syn

Front 109

What is the range of well-known port numbers?

Back 109

1-1023

Front 110

What is the typical range of ports used by Microsoft clients, and what is the range of ports called?

Back 110

1024-4999, ephemeral ports

Front 111

What is an IP socket? Provide an example.

Back 111

A socket is the combination of an IP address and a port number that designates a specific application on a specific host. 192.168.1.13:80

Front 112

What are the port numbers of FTP (data and control), SFTP/SSH, SMTP, Telnet, HTTP, HTTPS, and DNS?

Back 112

FTP data =20, FTP control =21, SFTP/SSH = 22, SMTP=25, Telnet = 23, HTTP = 80, HTTPs=443, DNS = 53

Front 113

What are the three popular interior dynamic routing protocols?

Back 113

Routing Information Protocol (RIP), Open Shortest Path First (OSPF), and Enhanced Interior Gateway Routing Protocol (EIGRP)

Front 114

Which routing protocol is used for small autonomous systems with minimal security concerns?

Back 114

RIP

Front 115

Which routing protocol is used for large autonomous systems that only use TCP/IP?

Back 115

OSPF

Front 116

What is the name of the Cisco Systems routing protocol that is not limited to TCP/IP routing?

Back 116

EIGRP

Front 117

What are the two types of routing protocols?

Back 117

Internal and external protocols.

Front 118

What is the primary metric of RIP?

Back 118

Number of hops needed to the destination host.

Front 119

What are the components of the metric used by OSPF to determine path choice?

Back 119

Cost, throughput, and traffic delays.

Front 120

Which interior routing protocol would you use if you have a moderately big corporate internet with strong security requirements?

Back 120

OSPF

Front 121

What are the components of the metric used by EIGRP to determine path choice?

Back 121

Interface bandwidth, load on the interface, delay, and reliability

Front 122

What is the predominant external dynamic routing protocol?

Back 122

Border Gateway Protocol (BGP)

Front 123

What is the name of the protocol that deals with supervisory messages at the Internet layer?

Back 123

Internal Control Message Protocol (ICMP)

Front 124

What is the name of at least one ICMP message?

Back 124

Ping, netstat, tracerout

Front 125

What is an ICMP echo request often called?

Back 125

Ping

Front 126

Networks using the MPLS standard making routing decisions using _________?

Back 126

Label switched paths

Front 127

What are the benefits of using MPLS?

Back 127

1) Reduces forwarding costs 2) premits traffic engineering 3) permits quality of service

Front 128

Would it be easy or hard to implement MPLS accross the entire internet and why/why not?

Back 128

It would be very difficult because you would have to coordinate with many, many ISPs on determination of label-switched paths. This coordination would be difficult as there will be conflicts between ISP priorities and network management philosophies."