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A+ Certification 901 > Networking Part 2 > Flashcards

Networking Part 2 Flashcards

1
Q

What is the textbook definition of RF?

A

Radio Frequency

Using wireless electromagnetic (EM) signals for data communications.

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2
Q

Are WI-FI nodes transmitters or receivers?

A

Both. As such, they need an antenna to propagate the waves.

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3
Q

What are the common IEEE WI-FI standards?

A
  • IEEE 802.11 a
  • IEEE 802.11 b
  • IEEE 802.11 g
  • IEEE 802.11 n
  • IEEE 802.11 ac
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4
Q

What is the IEEE 802.11 a standard?

A
  • Frequency: 5 GHz
  • Throughput: 54 Mbps
  • Indoor Range (m/ft): 35/115

Notes: Incompatible with other IEEE standards. Rarely used.

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5
Q

What is the IEEE 802.11 b standard?

A
  • Frequency: 2.4 GHz
  • Throughput: 11 Mbps
  • Indoor Range (m/ft): 35/115
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6
Q

What is the IEEE 802.11 g standard?

A
  • Frequency: 2.4 GHz
  • Throughput: 54 Mbps
  • Indoor Range (m/ft): 38/125
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7
Q

What is the IEEE 802.11 n standard?

A
  • Frequency: 2.4/5 GHz
  • Throughput: 65-150 Mbps
  • Indoor Range (m/ft): 70/230
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8
Q

What is the IEEE 802.11 ac standard?

A
  • Frequency: 5 GHz
  • Throughput: 86-780 Mbps
  • Indoor Range (m/ft): 35/115
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9
Q

What is the weakness of 2.4 GHz WI-FI?

A

Interference from things like cordless phones, microwaves, Bluetooth etc.

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10
Q

How many WI-FI channels are there on the 2.4 GHz band? How many non-overlapping channels?

A

There are 14 channels.

You can have up to 4 non-overlapping channels. To have all four channels, you must use 1,6,11,14.

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11
Q

Who regulates WI-FI channel availability in the U.S.?

A

The FCC

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12
Q

How many non-overlapping WI-FI channels are on the 5 GHz band?

A

23

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13
Q

What is WEP? What was it replace by?

A

Wired Equivalent Privacy

Uses initialization vector (encryption) plus a user defined password. Uses a 64 or 128 bit key. It’s weakness is that the is a 50/50 chance that the same vector will be used after 5,000 packets, which allows the password to be guessed by brute force.

Replaced by WPA (WI-FI Protected Access):

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14
Q

What is WPA?

A

WI-FI Protected Access

Encrypts via TKIP (Temporal Key Integrity Protocol): a new 128 bit key per packet

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15
Q

What is WPS?

A

WI-FI Protected Set-up

  • A feature of WPA
  • You can press a button on the wireless access point and another button on the device you want to connect at the same time to connect that device to the network. This is used in syncing Wii-motes to the Wii with the little red button.
  • Note that WPS can be broken into by brute force, but it is still better than WEP.
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16
Q

What is WPA 2?

A

Encrypts via AES (Advanced Encryption Standard). Keys range from 192-256 bits.

There are two versions of WPA 2:

  1. Personal: Uses a PSK (pre-shared key. Just like WPA 1)
  2. Enterprise: allows different authentication schemes like EAP and RADIUS

More difficult to slower, more difficult to configure, but more secure.

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17
Q

What features does a SOHO router (also called “multi-function router” or “integrated services router”)often have that a business router may not?

A
  • WI-FI Access Point
  • Switch
  • Firewall DHCP Server
  • VPN Server

Typically has just one public IP, which is shared among local users. Users are each given private non-routable IP addresses.

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18
Q

What is a firewall?

A

Hardware/software that screens network traffic.

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19
Q

What is DHCP?

A

Dynamic Host Configuration Protocol

Operates on UDP 67 and UDP 68

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20
Q

What is a gateway?

A

It is the internal IP address of the router. Accessing the gateway allows a machine to access things outside of the subnet it’s on, such as the internet or other subnets on the network.

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21
Q

What is NAT?

A

Network (Port) Address Translation

Translates between a machine’s private IP address and the network’s one public IP address, which allows the machine to access the internet. The internet can only see that one public IP address.

DNAT is Destination NAT. It translates to allow users on the internet to access a local machine on the network (such as a web server). It’s NAT in reverse.

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22
Q

What is port forwarding/port triggering?**

A

Forwarding: Any incoming traffic that attempts to communicate on this particular port (ex: UDP/TCP 3074) will be allowed through. (You essentially poke a hole in your firewall)

Triggering: Works the same as forwarding, but instead of a particular port, you create a range of ports that can be accessed or you create a rule to define the ports that can be accessed.

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23
Q

What is QoS?

A

Quality of Service

It is reserving or prioritizing bandwidth for a service to ensure consistent quality of service.

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24
Q

Is a SOHO router’s OS firmware or software?

A

Firmware. It is considered firmware because it is more permanent than a computer’s software OS.

(Also, remember to research a firmware upgrade before you do the upgrade. Sometimes it is better to wait.)

25
Q

What is UPnP

A

Universal Plug-and-Play

  • Used for things like appliances and such
  • Can automatically forward ports on your router to get on the network.
  • It creates extra vulnerabilities to malware if it gets on one of your machines. Since the router considers connections inside the network to be safe, the malware will be free to make outbound connections.
  • Unless you are using UPnP, make sure to disable it on your SOHO router to close that vulnerability.
26
Q

What are some basic security measures to take with SOHO routers?

A
  • Disable Web-based remote management.
  • Disable WPS
  • Disable any other unnecessary services, such as UPNP
  • Set strong passwords for router and WLAN
  • Change all defaults (SSID, IP range, etc.
  • Don’t give away details in the SSID, such as your name.
  • Update firmware.
27
Q

What is a LAN?

A

Local Area Network

“Area of high-speed connectivity contained within a single location.”

(Note: the business usually owns all the equipment of their LAN)

28
Q

What is a WAN?

A

Wide Area Network

“Two or more LANs that use a service provider to establish network connectivity.”

(Note: the business usually leases the WAN from the service provider)

  • The LANs are usually far apart. They could be in different cities, states, or even continents.
  • Technically, the internet is one giant WAN.
29
Q

What is a MAN?

A

Metropolitan Area Network

(Sometimes called a CAN: Campus Area Network)

Larger internetwork that spans multiple buildings or sites within a city. It is considered a subset of a WAN.

30
Q

What is a WLAN?

A

Wireless Local Area Network

“An area of high speed connectivity that is owned or run by the same individual or group that applies the IEEE802.11 standards (Brand name WI-FI)

31
Q

What is a WAP?

A

Wireless Access Point

(Also called a hotspot)

Important considerations:

  • Which 802.11 standards to support.
  • Concentration of access points.
  • Signal strength.
  • Interference (think 2.4 GHz frequency band)
32
Q

What is double NAT?

A

If your network is set of so that it connects to an access point and the access point connects to the router, then information form the computer will have to be translated twice before it gets to the internet, instead of just once.

Double NAT doesn’t have any significant impact on speed, but it can be a problem if you are using plug and play.

33
Q

What is PAN?

A

Personal Area Network

Includes things like:

  • NFC (Near Field Communication, such as Apple Pay).
  • Bluetooth
  • Infrared
34
Q

What are the types of internet connectivity?

A
  • Analog Modem: 1. Dial-up 2. Voice or Data 3. Max speed of 53 kbps 4. Analog to digital modulation
  • ISDN (Integrated Services Digital Network): 1. Max speed of 128 kbps 2. Requires a separate modem and special phones 3. Never became popular.
  • DSL (Digital Subscriber Line): 1. Digital Voice and data 2. Protocol used is PPPoE 3. Uses phone lines.
  • Broadband Cable: 1. Data over coax cable 2. Protocol used is DOCSIS.
    Fiber Internet: 1. Expensive 2. Requires more overhead.
  • Satellite: 1. Good for remote locations 2. Sensitive to weather (requires line-of-sight) 3. You pay for data used, not data speed.
35
Q

What is Tethering? What are some tethering methods?

A

Tethering is when a smartphone shares its internet connection with a laptop. The common example is when a phone creates a WI-FI hotspot. It used to be illegal, but not anymore.

  1. Phone natively supports tethering
  2. Jailbreaking/Rooting device
  3. 3rd party apps
36
Q

What is reverse tethering?

A

When your laptop shares its internet connection with your cell phone. (Less popular now that phones have WI-FI).

Most common method is to set up the laptop as a virtual WI-FI access point.

37
Q

What is Line-of- Sight Wireless Internet Service?

A

Wireless point-to-point Ethernet. Used to connect two buildings to the same network.

  • Useful in remote areas where Ethernet cables are impractical.
  • 5-150 Mbps speeds and can reach several miles.
  • Antennas need to be high enough to overcome the Fresnel zone. (The Fresnel zone is the area above and below the line of sight where objects, such as trees, can interfere with the signal).
38
Q

What is a Hub?

A

IT is a multi-port repeater (regenerates Ethernet signals).(Has been supplanted by the switch).

  • Operates on OSI layer 1
  • Good for diagnostic purposes
  • Unlike a switch the input for each port is put into the same collision domain. This means that two machines may have to share the same communication medium, which slows things down a lot. Switches have a separate collision domain for each port.
39
Q

What is a switch?

A

A combination and replacement for the hub and the bridge. (A switch creates a network).

  • Operates on OSI layer 2
  • The bridge segmented one collision domain into more than one.
  • Switches store a table of the MAC addresses for the computers connected to each port. This allows it to provide dedicated bandwidth to each port.
40
Q

What does ASIC stand for? What is it?

A

Application Specific Integrated Circuit

41
Q

What is a bridge?

A
  • Segments a collision domain into more than one.
  • originally, it was just a two port switch.
  • More recently, they are gateways
  • Basically, the modern use is to connect a remote part of the building to the rest of the network.
42
Q

What is a router?

A

It separates the local network from the internet, but it can also separate the local network into sub networks. For example, you may want to set up a subnet for guest WI-FI access and another for employee access. (A router connects networks).

  • Operates at OSI level 3
43
Q

What is a WAP?

A

Wireless Access Point

  • Provides connectivity using the IEEE802.11 standard
  • Many support PoE (Power over Ethernet)
  • If you have a lot of WAPs, use a Wireless LAN controller to control all of them from one place.
44
Q

What is PoE?

A

Power over Ethernet

  • Uses the IEEE 802.3af Ethernet standard
45
Q

What is an analog modem?

A

Modulates digital signals to analog for transmission over phone lines (and vise versa). They are used for dial-up internet connectivity.

46
Q

What is a firewall?

A

Selectively allows or blocks network traffic.
like IP addresses, port numbers, and other things.

  • Can come in the form of software or hardware.
  • Packet Filtering Firewalls allow or block traffic on the basis of IP addresses and port numbers. (uses layers 3 and 4)
  • Stateful Packet Inspection (SPI) Firewalls identify sessions and can enforce rules on higher level applications and services (uses layers 1-7)
47
Q

What is a patch panel?*

A

A patch panel provides modularity, which means that you can patch a machine into a switch.

An Ethernet cable is attached to a computer on one end and a patch panel on the other. (There may be other devices in between, but it will terminate at the patch panel.)

48
Q

What is a repeater/extender?

A

Breaks the 100 meter Ethernet barrier by providing another 100 meters.

  • some repeaters/extenders support PoE.
49
Q

What is EoP (Ethernet over Power)?

Also called Powerline Ethernet

A

Allows you to run 100-500 Mbps through your mains AC power. You use a powerline adapter on each end of the line.

This is helpful in reducing the need to run new cables.

50
Q

What are cable crimpers?

A

they are a handheld tool that look a lot like wire strippers. They are for terminating Ethernet cables into an RJ-45 or RJ-11 plug.

Cutting your own Ethernet cables allows you to save a lot of money and make them the length you want, instead of a standard length.

51
Q

What is a multimeter?

A

Used to measure electrical properties of an object. It measures voltage, current, and resistance.

Useful in verifying:
- DC power supply voltage

52
Q

What is a tone generator and probe?

A

Used to trace Ethernet cables to find out where they terminate. They can also verify continuity.

Often used in conjunction with troubleshooting and documentation.

53
Q

What is a cable tester?

A

Used to verify that a cable is working properly. It can also verify continuity.

54
Q

What is continuity?

A

Continuity means you have an unbroken signal from one end of the wire to the other.

A cable tester can tell you which cable has a physical problem and how far in the problem is.

55
Q

What is a punchdown/impact tool?

A

Used to terminate Ethernet cables.

56
Q

What is a loopback plug?

A

They are used to test network cables and switch ports. It tricks the machine into thinking it has a connection.

57
Q

What is a protocol analyzer?

A

Good way to visualize network traffic (wired or wireless)

Wireshark is a good protocol analyzer

58
Q

What is a WI-FI analyzer?

A

Allows you to create a floor plan and see where your WI-FI signal is strong and where it is weak.

  • Best if you use a phone app and walk around to test the connection in each area.
  • Some analyzers allow you to see information about other networks, such as what channel they’re on, what type of encryption they’re using, etc.
  • (Wifipinapple.com has some unique WI-FI tools)
59
Q

How do you identify problems with a cable tester?

A

A cable tester will show two rows of numbers. If the cable is good, it will show two identical sets of numbers. If it is not, it will be due to one of the following scenarios.

  • Open: There is an open in the circuit. The tester will have at least one missing number.
  • Short: The connection is grounded. You’ll see numbers repeated that shouldn’t be.
  • Miswire: The wrong wire is going to the wrong place. All the same numbers will be on each row, but in the wrong order.

A+ Certification 901 (9 decks)

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