Google - The Bits and Bytes of Computer Networking: Week 5

At a high level, cellular networks have a lot in common with the __ networks used for WiFi.

802.11

The set of specifications called the ___ "family" make up the set of technologies we call Wi-Fi.

802.11

Mesh networks allow you to deploy more access points to the "mesh" without having to run a __ to each of them - thus increasing the performance and range.

cable

With DSL, phone calls and __ transfer could occur at the same time on the same line.

data

The different 802.11 specifications (b, a, g, n, ac...) all operate with the same basic __ __ protocol, but how they operate at the __ layer varies. Each can have different ranges, use different modulation techniques, have different transmission bit rates, operate on different frequency bands, etc.

data link, physical

After the 4th address field in an 802.11 frame comes the __ __ section, which has all of the data of the __ further up the stack.

data payload, protocols

802.11 frame address fields: 1.) the Source field indicates the __ address of the sending device 2.) the intended ___ on the network 3.) a __ address 4.) a ___ address.

MAC, destination, receiver, transmitter

__ networks are a bit like ad-hoc ones since lots of devices communicate with each other wirelessly (forming a __) - but most mesh networks you'll encounter will be made up of only wirless access points, and will still be connected to a __ network.

Mesh, mesh, wired

True or false: "channels" can overlap.

TRUE

It wasn't until the advent of __ that the true potential of Internet was realized.

broadband

The term ___ refers to any connectivity technology that ISN'T dial-up internet.

broadband

Without __ technologies, the Internet as we know it today couldn't exist.

broadband

In FTTB, fiber data technologies are used for data delivery to an individual ___; after that, twisted pair copper cable is used.

building

In many situations, the ___ and receiver address (in an 802.11 frame) might be the same, and usually, the ___ and transmitter addresses are also the same - but this won't always be so, depending on the wireless network architecture (for example if Wireless access points relays these frames from one to another).

destination, source

MAC filterering doesn't help encryption of wireless traffic being sent through the air, but it does provide an extra barrier to unauthorized __ connecting to the network itself.

devices

Businesses invested in broadband early on out of necessity: the bandwidth of __-__ couldn't handle more than a few users.

dial-up

Ad-hoc networks can be very useful in __ situations, when all the infrastructure in an area is knocked out: disaster-relief workers can use these networks to communicate with each other while doing search-and rescue.

disaster

WEP (Wired Equivalent Privacy) is an __ technology that provides a very __ level of privacy.

encyrption, low

When your sending data on a wired link, there's inherent privacy: only the devices on the two __ of the link know what's being sent.

ends

WAN technologies are great when you need to transport large amounts of data across lots of sites: they are built to be super-___.

fast

Generally, ADSL lines have (faster / slower) download speeds and (faster / slower) upload speeds.

faster, slower

An 802.11 __ has many fields.

frame

The last field of an 802.11 frame is a __ __ __ field (FCS).

frame check sequence

The first field in an 802.11 frame is the __ __ field.

frame control

The Duration field (2nd field of an 802.11 field) specifies how long the total __ is, so the receiver knows how long to "___".

frame, listen

A __ __ is a certain section of the radio spectrum that's been agreed upon to be used for certain communications.

frequency band

Channels are individual, smaller sections of the overall __ __ used by a wireless network.

frequency band

Different 802.11 standards generally use the same basic protocol, but might operate at different ___ __.

frequency bands

Over the years, the phrase "T1" has come to mean any __ __ copper connection capable of speeds of 1.544 ___ per second, even if doesn't follow the original T1 specification.

twisted pair, megabits

WEP (Wired Equivalent Privacy) protects your data a little: like sending __ data over a wired connection.

unencrypted

With DSL, telephone companies were able to use the same infrastructure (as with dial-up): the twisted-pair copper of modern phone lines was capable of transmitting way more data than was needed for __-__-__ calls.

voice-to-voice

A _ __ __ acts like a single network but spans across multiple physical locations.

wide area network

The history of television is the opposite of that of Internet and phone: instead of going from wired to wireless, TV has gone from wireless to __.

wired

"Airplane mode" disables all __ networking at once: Bluetooth, WiFi, Cellular...

wireless

Association between a device and a wireless access point isn't just important for the wireless device to talk to a specific access point; it also allows for ___ transmissions to the wireless device to be sent by the right access point.

incoming

You can sometimes see ad-hoc networks in warehouse or ___ settings where pieces of equipment need to communicate with each other but not anything else.

industrial

An Optical Network Terminator (ONT) converts data from __ the fiber network understands to those that more traditional twisted-pair copper networks understand.

protocols

WANs use different ___ at the data __ layer to transfer data from one site to another: These protocols are the ones at work at the core of the Internet itself (instead of Ethernet). (Extra reading available about WAN protocols).

protocols, link

Despite auto-sensing and the possibility of manually specifying channels, channel congestion can still occur: especially in dense urban areas with lots of wireless networks in close __.

proximity

What does PSTN stand for?

public switched telephone network

Wireless networking devices communicate with each other through ___ waves.

radio

If you're troubleshooting an unreliable wirless network connection, keep in mind that wirless works by sending a __ signal between two __.

radio, antennas

If someone brings a device to you (the tech specialist) because it won't connect to a wireless network, the first thing you should check is whether the wireless __ has been __.

radio, disabled

The most important thing to remember is that networks that operate on the 5Ghz band are almost always faster, but have less of a __. Most of the 2.4Ghz networks are slightly __ and more susceptible to __, but usually cover a larger area.

range, slower, interference

The absolute maximum distance an electrical signal can travel across a copper cable before it degrades too much and requires a ____ is thousands of feet.

repeater

In FTTH, fiber is run to each individual ___ in a neighborhood or apartment building.

residence

In between the 3rd and 4th address fields in an 802.11 frame is the __ __ field, which is __ bits long and is used to keep track of ordering the frames.

sequence control, 16

Cable Internet technologies use a ___ bandwidth model: many users use shared bandwidth until the transmissions reach the ISP's core network.

shared

Today, most cable operators have upgraded their networks so that users won't notice __ bandwidth.

shared

One of the differences between cable broadband and other broadband solutions is that cable is a ___ ___ technology.

shared bandwidth

Mobile devices connect to their peripherals using __-___ wireless networks, the most common of which is ___.

short-range, Bluetooth

Point-to-point VPNs are also called __-_-__ VPNs.

site-to-site

With so many cloud solutions available, many businesses no longer require extreme high-speed connections between their __ (like with WAN).

sites

A point-to-point VPN establishes a VPN tunnel between two __. In this case, the VPN tunneling logic is handled by ___ devices at either side so users don't need to establish their own connections.

sites, network

Ad-hoc networks have some practical applications, e.g.: some ___ can establish ad-hoc networks with others in the area to exchange photos, videos, contact information (etc.)

smartphones

The problem of collision domains has been mostly solved on wired networks by __, which remember which computers live on which physical __, so traffic is only sent to the node it's intended for.

switches, interfaces

By the 1990's cable television infrastructure in the US was about the size of the public ___ system. Not long after, cable providers started tryng to figure out how to take a bite out of the Internet business.

telephone

With SDSL, the download and upload speeds are (different / the same).

the same

The radio signal of a wireless connection will get weaker the farther it has to travel, especially if it passes __, or __ off of things between the two antennas.

through, reflects

With wireless networking, anyone within range of the radio transmissions could hypothetically intercept any __. To solve this problem, __ was invented.

transmissions, WEP

By the time USENET was being developed, baud rates had increased to approximately __ bps.

300

With the T1 specification, AT&T invented a way to carry up to __ phone calls over a single piece of twisted pair copper.

24

The way a device is held or worn does not ever affect signal strength: true or false?

FALSE

The Receiver address (__ address field in an 802.11 frame) indicates the ___ address of the ___ point that should receive the frame.

3rd, MAC, access

How many address fields are there in an 802.11 frame?

4

WEP (Wired Equivalent Privacy) only uses __ bits for its encryption keys. This can usually be cracked in just a few minutes.

40

The Transmitter address (__ address field in an 802.11 frame) indicates the ___ address of whatever has just transmitted the frame.

4th, MAC

Each of the 24 phone channels of the T1 specification could carry data at speeds of __ kbps.

64

In terms of the networking model, 802.11 protocols define how to operate at the the __ and __ layers.

physical, data link

The PSTN (pulic switched telephone network) is sometimes referred to as the P__ O__ T__ S__.

plain old telephone service

A popular alternative to WAN technologies are __-__-___ ___s.

point-to-point VPN

In North America, __ radio communications operate between 88 and 108 MHz.

FM

The frequency band of 88 to 108 MHz (in North America) is called the __ __ __.

FM broadcast band

With __ __, you configure your access points to allow connections only from trusted MAC addresses.

MAC filtering

Since all addresses in an 802.11 frame are __ addresses, each of those 4 fields is __ bytes long.

MAC, 6

WPA2 uses a __-bit key.

256

By default, WPA (WiFi Protected Access) uses a __-bit key.

128

The first 802.11 frame field, called the Frame Control field, is __ bits long and contains sub-fields used to describe how the frame itself should be __ (like what __ of the 802.11 was used).

16, processed, version

Wi-Fi networks operate on different frequency bands, but most commonly on the ___ __ band and ___ __ band.

2.4GHz, 5GHz

When we talk about the 2.4 GHz band in wireless networking, we are really referring to roughly 2.4 GHz to __ GHz

2.5

In an 802.11b network, channels _ , _ and _ are the only ones that never overlap at all.

1, 6, 11

Since wireless networks don't have cables, there are no __ interfaces to connect to - so there can't be anything like a "wireless switch".

physical

ADSL stands for _____.

Aysmmetric Digital Subscriber Line

CMTS stands for ______.

Cable Modem Termination System

Other broadband solutions (beyond T-carrier lines) exist for both businesses and consumers: D__, C__ broadband, F___ connections.

DSL, cable, fiber

DSL technologies also use modems, known as DSLAMS (__ __ __ __ __ __).

Digital Subscriber Line Access Multiplexers

What is the second field of an 802.11 frame? (after the Frame Control field): ____ field

Duration

Ad-hoc networks are the simplest type of wireless network, and ALSO, they're the most common!: true or false?

FALSE

Early modems had very high baud rates: true or false?

FALSE

__ allows a transmission to travel much further without degradation of the signal.

Fiber

What does FTTX stand for?

Fiber to the X

What does FTTB stand for?

Fiber to the building, business or basement

What does FTTH stand for?

Fiber to the home

What does FTTN stand for?

Fiber to the neightborhood

The most common specifications for how wireless networking devices should communicate are defined by the ___ __ standards.

IEEE 802.11

___ is part of the IEEE 802 set of local area network (LAN) protocols, and specifies the set of MAC and physical layer protocols for implementing wireless LAN (WLAN) Wi-Fi computer communication in various frequencies, including but not limited to 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands.

IEEE 802.11

The "local loop" is the area that connects a demarcation point to the ISP core network and the __ at large.

Internet

__ __ __ (IoT) devices communicate with each other using ___ and / or IoT network __.

Internet of Things, WiFi, protocols

Z-wave, Zigbee and Thread are examples of __ (Internet of Things) __.

IoT, protocols

Another common way to secure wireless networks is through __ filtering.

MAC

Modems (modulator / demodulators) take data that computers understand and turn it into audible wavelengths that can be transmitted over ___.

POTS

SDSL stands for _____.

Symmetric Digital Subscriber Line

In ad-hoc networks, all nodes help pass along messages: true or false?

TRUE

In some places, using a cellular network for Internet access is the most common way of connecting: true or false?

TRUE

T1 or ___ ___ _ was the first T-carrier specification

Transmission System 1

What does WPA stand for?

WiFi Protected Access

___ is one of the oldest working network communication platforms; It was a precursor to dial-up networks and was invented by two Duke university students in 1979.

USENET

Instead of WANs, companies can use point-to-point ___ to make sure their different sites can still communicate.

VPNs

Asynchronous Transfer Mode is a ___ protocol

WAN

Frame Relay is a __ protocol.

WAN

The __ encyrption standard is a very weak algorithm, easy to break.

WEP

A __ consists of 1 or more access points which act as bridges between wireless and wired networks: The wired network operates as a normal LAN and contains the __ Internet link

WLAN, outbound

The most common type of wirless network in the business world is a ___ or ___ ___.

WLAN, wireless LAN

In ___ (or ___ ___), one or more access points act as a bridge between a wireless and a wired network.

WLANs, wireless LANs

WEP (Wired Equivalent Privacy) was quickly replaced by __ ( __ __ __).

WPA, WiFi Protected Access

Today the most common encryption algorithm for networks is __,

WPA2

What does WAN stand for?

Wide Area Network

What does WEP stand for?

Wired Equivalent Privacy

A single wireless network might have lots of different ___ points, to cover a large area.

access

A wireless __ __ is a devices that bridges the wireless and wired portions of a network.

access point

Devices on a wireless network will association with a certain __ __ - normally, the one they're physically closest to, but it can be determined by other things (signal strength, wireless interference, etc.)

access point

There are 4 address fields in an 802.11 frame because there needs to be room to indicate which wireless __ __ should be processing the frame.

access point

The most common setup (architecture) of a wireless network includes devices called ___ ___.

access points

Each newer version of the 802.11 specifications has generally seen some improvement, such as higher ___ speeds or the ability of more devices to use the network ___.

access, simultaneously

In ___ wireless networks, nodes all speak directly to each other.

ad-hoc

___ networks are the simplest type of wireless network: They don't have any sort of supporting network infrastructure; every device communication with every other device in range.

ad-hoc

There are a few main ways a wireless network can be configured: _-__ networks, ___ and ___ networks.

ad-hoc, WLANs, mesh

In an 802.11 frame: After the Duration field, there are 4 ___ fields.

address

There are lots of different 802.11 specifications. The most common ones that you'll encounter are: 802.11_, 802.11_, 802.11_, 802.11_ and 802.11__ (listed in the order they were adopted)

b, a, g, n, ac

The __ __ of cellular networking can be though of as "__ __", but with a much larger range.

cell towers, access points

Cellular networks are based around the concept of __: each one is assigned a specific ___ __ for use, and neighboring cells are set up to use bands that don't __.

cells, frequency band, overlap

Just as there are many 802.11 specifications, there are lots of different __ specifications.

cellular

Mobile devices use wireless networks to communicate with Internet and other devices: C__ N__, W__, B__ or IoT (__ __ __) protocols.

cellular networks, WiFi, Bluetooth, Internet of Things

Not only phones, but also some tablets and even laptops have ___ antennas, as well as high-end __.

cellular, automobiles

Another popular form of wireless networking is ___ networking, also called "__ networking".

cellular, mobile

Just like WiFi, __ networking operates over __ waves, and there are specific __ bands reserved for cellular transmissions.

cellular, radio, frequency

Between 2.4 GHz and 2.5 GHz there are a number of __, each with a width of a certain MHz. (The number of actual channels depends on where in the world you are, due to regulartory differences).

channels

The concept of __ is one of the most important things to understand about wireless networking.

channels

___ are individual, smaller sections of the overall frequency band used by a wireless network.

channels

The Frame Check Sequence field (last field of an 802.11 frame) contains a ___ used for a __ __ check, just like how Ethernet does it.

checksum, cyclical redundancy

In recent years, companies have been moving more and more of their internal services into the ___, which lets companies outsource all or part of their infrastructure, for other companies to manage.

cloud

In the past, a company would have to have its own e-mail server if they wanted an email presence at all; Now, you can just have a __ hosting provider host your email for you.

cloud

When 2 or more communications occur at the same time (in a network segment), it's called a __. After such an event, all devices stop transmissions, wait a random amount of time and try again.

collision

A __ __ is any one network segment where one computer can interrupt another.

collision domain

Channels help address the problem of __ __.

collision domains

In troubleshooting wireless connectivity problems or slow-downs in the network, you want to avoid __ __ whenever you can.

collision domains

Today, most wireless networking equipment is built to automatically sense what channels are most __; Some access points only perform this analysis when they start up; others will dynamically change their __ as needed.

congested, channel

The number of bits in an encryption __ corresponds to how secure it is: the more bits, the longer it takes to crack.

key

One of the biggest difference between WiFi and cellular networks: the radio wave frequencies used for cellular can travel __ distances: many kilometers or miles.

longer

___ networks are like a hybrid between ad-hoc and WLAN networks:

mesh

A __ connection is one in which you are charged based on the amount of data used.

metered

WiFi is a (metered / nonmetered) connection.

nonmetered

It's not important to memorize all the numbers related to overlaping channels and 802.11 specifications: the point is to understand how collision domains are a necessary problem with ALL wireless networks - and you can use your knowledge of this to __ wireless deployments. Make sure your own __ __ as well as those of neighboring networks overlap as little as possible.

optimize, access points

Understanding how channels __ for all the 802.11 specifications is a way you can help troubleshoot wireless connectivity problems or slow-downs in the network.

overlap

When you connect a wireless peripheral to a device it is called __ the devices.

pairing

Further developments in SDSL technology have led to HDSL (__________).

High bit-rate Digital Subscriber Lines

CMTS connects lots of different cable connections to an __'s core network.

ISP

If you ever need to know more about a specific DSL line, you should contact the ___ for more details.

ISP

Cable companies realized the the ___ cables used used for cable TV delivery could transfer much more __ than what was needed for TV viewing.

coaxial, data

When a DSLAM (digital subscriber line access multiplexer) is powered on, it establishes a ___ that isn't ___ down until it's powered off.

connection, torn

For Inter-ISP connections, different fiber technologies have replaced older, __-based ones.

copper

In FTTN, a fiber cable reaches a cabinet that servers a certain amount of the populaton: twisted pair __ or __ might be used after that.

copper, coaxial

Unless you are a __ ___ at an ISP, you probably won't have to directly Interact with WAN protocols.

data engineer

As different aspects of the Internet, like the World Wide Web, became more complex, they also required ever increasing __ __ rates.

data transfer

Like dial-up models, DSLAMS establish __ connections across phone __; but unlike dial-up connections, they're usually __-running.

data, lines, long

T-carrier technologies require ___ lines, which makes them more expensive. They're normally only used by businesses.

dedicated

Certain implementations of fiber connections can travel many, many miles before a signal ___.

degrades

A __-_ connection uses POTS (plain old telephone service) for data transfer. The connection is established by actually dialling a phone number.

dial-up

Broadband connections are almost always faster than the fastest __-__ connections, and are always __.

dial-up, on

ADSL lines have (the same / different) speeds for outbound and incoming data.

different

What does DSL stand for?

digital subscriber line

Broadband connections are long-lasting connections that don't need to be __ with each use. They are essentially links that are always present.

established

Producing and laying fiber is a lot more ___ than copper cables, so for a long time it was only used by ISPs for their core networks, or in data centers.

expensive

By using __ that don't interfere with TV broadcasts, cable-based Internet access technologies could deliver high-speed Internet access: this is called cable ___.

frequencies, broadband

In the days of dial-up, even a single __ could take many seconds to download and display.

image

By the time dial-up access became common in households (1990's), the buad rate had increased to 14.4 __

kbps

Fiber uses __ for data transmission instead of electrical currents.

light

A "local loop" (area between a demarcation point and ISP core network) could be a T-carrier ___ or high-speed optical line to the ISP's local regional office.

line

Imagine 2 networks, phsically distant: Each ends at a demarcation point, where an ISP network takes over. The area between the demarcation point and ISP's core network is called a __ __.

local loop

A single T1 data line could transfer data at speeds of 1.544 __ bits per second

mega

Two megabytes is over 16 (thousand / million / billion) bits.

million

There are lots of types of DSL available. They vary in a (major / minor) way.

minor

Transferring data through a dial-up connection is done through devices called __.

modems

What does "modem" stand for? __/__

modulator/demodulator

If you have a WAN, it will seem like all of your computers are in the same ___ location - but they're not!

physical

WAN protocols normally define how both the __ and __ __ layers need to operate when they're deployed.

physical, data link

What does POTS stand for?

plain old telephone service

What does FTTP stand for?

Fiber to the premises

HDSL technologies provision speeds above ____ mbps.

1.544

By the late 1950's, computers could generally only send each other data across a phone line at a rate of ___ bps (bits per second)

110

The first cable television technologies were developed in the US in the late ___'s.

1940

For a long time, the two most common DSL types were ___ and ___.

ADSL, SDSL

In 1984, the ___ communications ___ Act was published, which deregulated the cable television business and caused a massive boom.

Cable, Policy

By operating at a frequency range that didn't interfere with normal phone calls, __ (or __ __ __) technology was able to send much more data across the wire than dial-up techologies could.

DSL, digital subscriber line

Instead of a modem, the demarcation point for fiber technologies is an ONT, or ______.

Optical Network Terminator

What does ONT stand for?

Optical Network Terminator

FTTH or FTTB may also both be referred to as FTT_. (Fiber to the ___)

P, premises

With DSL and dial-up connections, the connetion from your home or business goes direction to a __ __, or __ (historically these were where swtichboard operators worked).

central office, CO

By the mid-1990's, it had become common for businesses that needed Internet to use various _-__ technologies, which were originally developed to transmit multiple phone calls over a single link.

T-carrier

__-___ technologies were originally invented by AT&T to transmit multiple phone calls over a single cable link.

T-carrier

Most SDSL technologies have an upper cap of 1.544 mbps, which is the same as a ___ line.

T1

Originally, __ was only used to connect different Telecom company sites to each other, and to connect these companies to other telecom companies. Later, businesses started using them.

T1

Multiple T1 lines were combined in one link: a __ is 28 T1s, all multiplexed, achieving a throughput speed of 44.736 mbps.

T3

A whole city block or an entire subdivision could share cable bandwidth: true or false?

TRUE

You can still find T-carrier technologies in use today, though other broadband technologies now surpass them, in general: true or false?

TRUE

__ technologies usually require that you contract a link across the Internet from your ISP, which handles sending data from site to site.

WAN

HDLC is a ___ protocol, and it stants for _____.

WAN, High-Level Data Link Control

Technologies like DSL and dial-up that connect directly to a CO can guarantee ___, since it's point-to-point.

bandwidth

There are many variations in DSL tecnology, offering different __ options and operating __.

bandwidth, distances

A __ __ is a measurement of how many bits of information can be passed across a phone line in a second.

baud rate

Cable Internet connections are usually managed by a __ ___, which is a device that sits at the edge of a consumer's network and connects it to the Cable Modem Termination System (CMTS).

cable modem

Small business offices now generally use __ broadband or ___ connections, which are cheaper than T-carrier.

cable, fiber