A university needs to link its London and Manchester campuses into one network. Why is a WAN needed rather than a LAN?
The campuses are a large distance apart
Which of these is an advantage of connecting a company's computers into a LAN instead of leaving them stand-alone?
Files can be accessed from any computer on the network
Which of these is a disadvantage of connecting computers together in a network?
A virus can spread quickly to every computer on the network
How are the separate networks in a WAN usually linked over long distances?
By leased lines rented from telephone companies
Why is the Internet described as a WAN?
It links many networks across the world
Which term describes a network that operates on a single site, such as a school or hotel, and uses its own cabling system?
LAN
What is meant by a WAN?
Two or more networks connected together over a large distance
What is meant by a stand-alone computer?
A computer that has no connection to a network or the Internet
What does the abbreviation WAN stand for?
Wide Area Network
Which of these organisations is most likely to use a WAN?
A bank with branches in several cities
A company stores all of its files on a server so that every computer on its LAN can use them. What is an advantage of doing this?
Data is easy to back up because it is stored centrally
Which term describes the amount of data that can be transferred over a network connection each second?
Bandwidth
What is meant by latency?
The delay between sending data and receiving a response
What is meant by 'megabits per second'?
A unit of network speed equal to one million bits per second
Which unit is used to measure the speed of a network connection?
Bits per second
What does the abbreviation Mbps stand for?
Megabits per second
A connection is described as having a high bandwidth. What does this mean?
A large amount of data can be sent each second
A connection has a bandwidth of 2 Gbps. How many bits per second is this?
2,000,000,000
A file size given in megabytes is multiplied by 8 before it is divided by the transmission rate in megabits per second. Why?
There are eight bits in one byte
A 40 MB file is downloaded over a 16 Mbps connection. How long does it take?
20 seconds
Which expression calculates how long a file takes to transfer?
File size in bits divided by transmission rate in bits per second
Which connection would transfer a large file in the shortest time?
1.2 Gbps
What is the name for how long it takes to send a document from one device to another over a network?
Transfer time
What is meant by 'gigabit per second'?
A unit of network speed equal to one billion bits per second
What is meant by 'kilobit per second'?
A unit of network speed equal to one thousand bits per second
A file of 60 MB is downloaded over a connection with a bandwidth of 40 Mbps. How long does the download take?
12 seconds
A player presses a key and the action on screen happens half a second later, even though the connection has a high bandwidth. What does this delay show?
The connection has a high latency
A 24 MB file is sent over a network in 16 seconds. What is the transmission rate in Mbps?
12 Mbps
A file takes 30 seconds to download over a 20 Mbps connection. What is the size of the file in megabytes?
75 MB
Two files are sent over the same connection. The second file is three times the size of the first. How does the transfer time compare?
The larger file takes three times as long
The same file is downloaded first over a 10 Mbps connection and then over a 40 Mbps connection. How does the second download compare?
It takes one quarter of the time
Which feature of fibre optic cable allows it to carry data at a higher bandwidth than copper cable?
It carries data as pulses of light
A video editor needs to copy a very large file between two computers on the same network. Which connection will transfer the file most quickly?
A wired link with high bandwidth
Why does a wired Ethernet connection usually have lower latency than a wireless connection?
The cable reduces interference
Which is a disadvantage of using wired connectivity compared with wireless connectivity?
Devices can only be placed where a cable reaches
What is meant by 'latency'?
The delay between data being sent and it arriving at its destination
Which term describes the maximum distance over which data can be transmitted before the signal becomes too weak?
Range
What is meant by 'fibre optic cable'?
A cable that transmits data as pulses of light and can carry it over long distances
Fibre optic cable carries data along thin strands of which material?
Glass
A factory has machines that create strong electrical interference. Why is fibre optic cable the best choice for its network cabling?
Light signals are unaffected by electrical interference
Why can a fibre optic cable carry data over a longer distance than a copper cable before the signal needs to be boosted?
The signal weakens less as it travels through the cable
What is meant by bandwidth?
The amount of data that can be transferred in a given time
A network manager is choosing between two wired connections for an online game server. Connection A has high bandwidth and high latency. Connection B has lower bandwidth and low latency. Which connection is better for the game and why?
Connection B because low latency reduces delays
Why can a wired Ethernet connection usually have a higher bandwidth than a wireless connection?
The cable gives data a dedicated path
What is meant by Ethernet?
A family of standards that describe how data is formatted for transmission on the same network
Which term means the amount of data that can be transferred along a connection in a given time?
Bandwidth
Which term describes the time delay between a device sending data and the reply arriving?
Latency
Why does a wired connection usually give a more reliable transfer than a wireless connection in the same room?
The signal is not affected by interference from other devices
Why is a wired network usually harder for an attacker to intercept than a wireless network?
The attacker must physically connect to the cable
Ten computers in a school office download a large file at the same time. Each download is slower than when one computer does it alone. Why?
The bandwidth is shared between the computers
Which type of wave is used to carry data in a wireless network?
Radio waves
What is the main purpose of a wireless access point?
To connect wireless devices to a wired network
A laptop gets a strong Wi-Fi signal in one room but a weak signal in a room behind a thick stone wall. What best explains this?
Radio waves are blocked or absorbed by solid walls
A player notices a delay between pressing a button and the action appearing on screen while playing online over Wi-Fi. Which characteristic of the connection causes this?
High latency
Several people stream films at the same time on one home Wi-Fi and the picture quality drops. What is the cause?
There is not enough bandwidth
Which is a performance advantage of a wired connection compared with a wireless connection?
It is less affected by interference from other devices
A laptop's Wi-Fi signal always drops when a microwave oven in the next room is switched on. What is this an example of?
Interference
What is meant by latency?
The delay between sending data and receiving a response
What is meant by bandwidth?
The maximum amount of data that can be transmitted over a connection in a given time
Which term describes a wireless technology that lets two devices link directly to each other over a short range of about 10 metres, for example a phone and a pair of wireless headphones?
Bluetooth
What is meant by Zigbee?
A low power wireless technology used for home automation that forms a mesh network
What is meant by NFC?
A wireless technology that works only over a few centimetres and is used for contactless payments and travel cards
A customer pays by holding a phone against a card reader for a moment. Which wireless technology does the phone use?
NFC
Sensors in a smart heating system send a few bytes of data each minute and must run for years on one battery. Why is Zigbee suitable for this?
It uses very little power and sends data at a low rate
A Bluetooth speaker plays music clearly from a phone in the same room but stops when the phone is taken outside. What explains this?
Bluetooth has a short range, so the signal becomes too weak
A tablet has no socket for a network cable but it can still join the school's Wi-Fi network. Which piece of hardware makes this possible?
A wireless network interface card
Which term describes a network layout in which every device has its own cable running to a central switch?
Star topology
What is the name for the component fitted at each end of a bus topology network to absorb signals and stop them reflecting back along the cable?
Terminator
Which term describes a network layout in which every device is connected directly to every other device?
Full mesh topology
What is meant by a bus topology?
All devices connect to a single shared coaxial cable
What is meant by a partial mesh topology?
Devices connect to several other devices, but not to all of them
What is meant by a node?
A device such as a computer or printer on a network
In a star topology, what happens to the rest of the network if one device's cable fails?
The other devices are not affected
In a bus topology, what are the computers and other devices connected to?
A single coaxial cable
What is the purpose of terminators in a bus topology?
To absorb signals so they do not reflect back
Why does a star topology transfer data quickly?
Each cable is not shared with other computers
Why can a bus topology be a security risk?
Any device can view all data on the cable
Why is a mesh topology described as resilient?
Data can take another route if a connection fails
In a wireless mesh network, how many nodes need a wired connection to the Internet?
Only one node needs a wired connection
In a star topology, what happens if the central switch fails?
No device can send data to any other device
Why is a bus topology usually cheaper to install than a star topology?
It needs less cable than a star topology
In a mesh network, what do the nodes do with data that they receive?
They pass it on towards its destination
What happens to a wireless mesh network as more nodes are added?
There are more routes for data to travel through
Which term describes the set of rules that allows devices to communicate over a network?
Protocol
What is meant by HTTPS?
A secure version of HTTP that encrypts data before it is sent
What is meant by the internet layer of the TCP/IP model?
The layer that routes packets between networks using their addresses
Desktop computers in a school office are connected to the network using copper cables. Which protocol is used for this connection?
Ethernet
What is the main purpose of the HTTP protocol?
Requesting and receiving web pages from a web server
An online shop asks customers to enter their bank card details. Why should the shop use HTTPS?
It encrypts the details so they cannot be read if intercepted
What is FTP used for on a network?
Sending and retrieving files to and from a server
An employee writes an email in their email program and clicks send. Which protocol sends the message to the mail server?
SMTP
A student wants to read their email on a phone, a laptop and a school computer and see the same messages on each device. Which protocol should be used?
IMAP
Which layer of the TCP/IP model is responsible for routing packets to their destination?
Internet layer
What does the transport layer do with data when a message is sent over a network?
It splits data into packets and joins them back together
Which list shows the four layers of the TCP/IP model in the correct order from top to bottom?
Application, transport, internet, link
A computer receives a data packet. Which layer removes the MAC address before passing the packet upwards?
Link layer
Which group of protocols all operate in the application layer of the TCP/IP model?
HTTP, FTP and SMTP
A packet is lost on its journey across a network. Which layer detects the error and resends the packet?
Transport layer
A company replaces its network routers with models from a different manufacturer. Why is this likely to work without changing the rest of the system?
Each layer is self-contained so it can be changed on its own
The transport layer divides a message into packets and gives each one a number. Why are these numbers added?
So the packets can be put back into the correct order
A tablet connects to a wireless access point so it can reach the school network. How is the data carried between the tablet and the access point?
As radio waves
A user has email set up on one laptop only. Each message is downloaded to the laptop and then deleted from the mail server. Which protocol is being used?
POP3
Which two protocols operate in the link layer of the TCP/IP model?
Ethernet and Wi-Fi
Why do all devices on a network need to use the same protocols?
So that each device can understand the data sent by the others
Which protocol divides a message into packets, reassembles them at the destination and resends any that are lost?
TCP
What is meant by the application layer?
The layer where applications such as web browsers and email clients create the data that is to be sent
A customer enters their bank card details on an online shop's payment page. Which protocol keeps these details secure while they are sent?
HTTPS
A student can read the same emails on a phone, a tablet and a school computer. Which email protocol allows this?
IMAP
A user has just downloaded all of their new emails using POP3. What has happened to those messages on the mail server?
They are removed from the server once they are downloaded
Which layer of the TCP/IP model adds the source and destination IP addresses to a packet?
Internet layer
Why is network communication divided into separate layers in the TCP/IP model?
So that changing one layer does not affect the others
Which term describes the method of sending data where a file is split into fixed size chunks that can each travel by a different route to the destination?
Packet switching
What is the name for the section at the start of a data packet that stores the destination IP address, the sequence number and error checking data?
Header
What is meant by a router?
A node that forwards packets from one network to another by choosing a route for them
What is the name for a fixed size block of data that is sent across the internet and reassembled in the correct order by the receiver?
Packet
What is meant by the sequence number in a packet?
A value that shows the position of the packet so the receiver can put the packets back into the correct order
A telephone call sets up a dedicated connection that is kept for the whole call. What is this method called?
Circuit switching
Which statement describes how the packets of one file travel across the internet?
Packets can take different routes to the destination
A packet arrives at the recipient computer and fails the error check. What happens to this packet?
It is requested to be sent again
Why are internet routers compared to a mail sorting office?
They pass each packet on towards its destination
What term describes each point on a network diagram, such as a computer or a router?
A node
Why is packet switching used instead of circuit switching for the internet?
A dedicated line for every user would need too many connections
Why does each packet include the destination IP address?
So routers know where to send the packet
A packet arrives at a computer and the computer needs to send a reply. Which part of the packet tells it where to send the reply?
The source IP address
A router that packets usually pass through stops working. What happens to a packet that would have gone through it?
It is sent along a different route to the destination
Why does the header of each packet contain error checking data?
So the recipient can check whether the packet was corrupted on the way
Why is a file split into packets before it is sent across the internet?
So each part can be sent by a route that is free
What is the name for the unique number given to every device on a network so that data can be sent to it?
IP address
What is meant by an IPv4 address?
A 32-bit address made of four numbers separated by dots
Which term describes an address that is 128 bits long and written as groups of hexadecimal digits separated by colons?
IPv6 address
How many bits are used in an IPv4 address?
32 bits
Which of these is a valid IPv4 address?
192.168.0.1
Data is sent from a computer on one network to a computer on another network. Which device uses IP addresses to forward the data between the networks?
A router
A home router is switched off and, when it reconnects, it is given a different public IP address. What is this type of address called?
A dynamic IP address
Why must every device connected to the internet have its own unique IP address?
So that data can be sent to the correct device
A student uses a laptop on their home network. They take it on holiday and connect it to a hotel network. Why does the laptop now have a different IP address?
The laptop is now on a different network, which gives it a new address
Which statement best describes the internet?
A large number of interconnected networks
Why does every device connected to the internet need an IP address?
So data can be sent to the correct device
An IPv4 address is written as four numbers separated by dots. What is the range of each of these numbers?
0 to 255
How is an IPv6 address different from an IPv4 address?
It is 128 bits long and written in hexadecimal
A user types a web address into a browser. What is the role of a DNS server?
It translates the domain name into an IP address
What is the main job of a router in a network?
To forward packets towards their destination address
Packets from a single file often arrive at the destination out of order. Why is this?
Different packets can travel along different routes
A student uses a laptop at home, then takes it on holiday and connects it to a different network. What happens to the laptop's IP address?
It is given a new IP address by the new network
What is meant by an IP address?
A number given to a device on a network so that data can be sent to and from it
Which term describes a device that forwards packets between networks so that data reaches the correct destination?
Router
What is meant by packet switching?
Data is split into packets that may take different routes and are put back in order at the destination
What is meant by a dynamic IP address?
An address that can change each time a device reconnects to the internet
What is the name for a word or phrase used to refer to an IP address so that users do not have to type the numbers?
Domain name
A file is split into packets before being sent across the internet. Which piece of information in each packet header allows the receiving device to put the packets back into the correct order?
The sequence number of the packet
A packet arrives at the receiving device but the error checking data shows that it was corrupted on the way. What happens next?
The packet is requested to be sent again
A DNS server receives a request for a web address that is not in its own database. What does it do?