Cambridge International A Level Information Technology
Answers to Student’s Book
Third-party websites and resources referred to in this publication have not been endorsed by Cambridge
International Education.
The questions, example answers, marks awarded and/or comments that appear in this book were written by the
authors. In examination, the way marks would be awarded to answers like these may be different.
12
IT in society
Activity 12a
The use of a credit card involves the temporary loan of the amount from the issuing bank, so the buyer does not need
to have enough funds to cover the cost of buying the goods. The use of a debit card requires that funds be taken from
the buyer’s account, so the buyer must have enough funds in the account to pay for the goods.
Activity 12b
1
A distributed ledger database is spread across several computing devices or nodes on a peer-to-peer network.
Every node has an identical copy of the database.
2
A blockchain will contain details of the previous transactions and a record of the latest transaction. It also has a
timestamp and the key needed to access it.
Activity 12c
1
Digital currencies are decentralised and there is no authority that regulates them. They are peer-to-peer and use
blockchains stored on every node on the network. Transactions cannot be reversed and are anonymous.
2
All nodes verify the transactions and they cannot be reversed.
Activity 12d
They are irreversible. Many users remain anonymous and may not return mistaken payments because they cannot be
traced.
Activity 12e
1
It is an electronic contract encoded in a blockchain as a distributed ledger. The details in the blockchain ensure
that the contract conditions are met before any money is transferred.
2
The contract details can be seen by all participants at any time and cannot be altered without the consent of all
the parties involved in the contract.
Activity 12f
1
A collection of data, which can be numbers representing values or be collections of descriptions, images,
documents or files.
2
Artificial neural networks can automatically create new relationships in very large collections of data as they
learn from the data being processed.
Activity 12g
1
Data mining only works with very large amounts of data, where overall trends and patterns can be discovered.
2
Working with vast amounts of data requires much computing power that uses expensive computing devices and
storage systems and requires highly skilled personnel to operate.
Cambridge International AS Level Information Technology
© Brian Gillinder / Hodder & Stoughton Ltd
1
Activity 12h
Web 2.0 emphasises the use of content created by users and is cloud-based using web browsers. Websites using Web
2.0 allow interaction between users, who can label or tag images, videos or other websites to draw the attention of
other users. Because all users can add content, it has encouraged discussion and debate.
Activity 12i
IM does not normally use end-to-end encryption and can be stored unencrypted on the provider’s servers for some
time so may be accessed by third parties.
Activity 12j
A one-time password (OTP) can be set by text message to a (smart)phone when the user tries to log in to the account.
The OTP has to be entered by the user to complete the login process.
Activity 12k
1
The sender and recipient do not have to be online at the same time. An email message is sent to a server, where
it is stored and then sent on (forwarded) to the recipient when requested.
2
The @ character separates the local address, which is user’s unique identifier, from the domain section. The
domain section gives the name of the organisation that holds the user’s email box. The domain section shows the
top-level domain and may indicate the country of origin.
3
Webmail can be used from any computing device with internet access. There is no need for a user to carry a
computing device when travelling because many hotels and cafes have computers that customers can use. Any
compatible web browser can be used and there is no need to set up or configure a dedicated email client or app,
which can be quite difficult.
4
Webmail can be read by third parties if the connection is not secure. Webmail can be analysed by the same
automatic systems that check user web activity, so using webmail can expose confidential messages to
unauthorised people.
Activity 12l
Social media can expose and display the views and behaviour of employees and prospective employees. Employees
can make good or bad comments about their employer, which may be seen by a wide audience and can have an effect
on the employer’s business. The employer may not approve of their comments nor be able to answer. Employers can
gather background information about prospective employees from their social-media posts.
Activity 12m
1
Most platforms do not carry out background checks on users applying for an account/profile, so people can set
up an account with false details. Often, only a valid email address is required.
2
There are so many contacts that children can make that it is very difficult for parents to check them all. Parents
cannot watch their children all the time so some unwanted contact can occur when they are not overseeing their
children’s access to social media. Children do not always report inappropriate contacts to parents.
Activity 12n
Personal information can be made public, or can be used for fraud or blackmail. Posts by others can be anonymous
and may be critical or hurtful and seen by all contacts. Cyberbullying and stalking can cause depression, low selfesteem and physical insecurity.
Cambridge International A Level Information Technology © Brian Gillinder / Hodder & Stoughton Ltd
Activity 12o
VAR interrupts the flow of game with pauses while decisions are reviewed. The decisions of the on-field referee can
be reviewed, changed, reversed or over-ruled, which removes some of the enjoyment and spontaneity of the game.
The use of VAR can be intrusive and ‘too clinical’, which takes away the fast-flowing action aspects of the game.
Activity 12p
The surgeon can wear a headset with head-up displays and overlays of cameras that zoom into the eye. Augmented
reality can enhance the information that is given to the surgeon about the positioning and placing of surgical
instruments within the eye. Surgical instruments and tools can be precisely controlled by movements of the surgeon’s
hands inside robotic gloves.
Activity 12q
People can access online banking from home with no need to travel to a bank. Speech recognition and text-to-speech
software have enabled visually impaired people to have access to online banking systems. Physically disabled people
can also use this software as well as adapted input devices such as sip-and-puff to control the computing devices.
Activity 12r
1
Data can be shown in graphs and charts and can determine trends in the financial growth of the business.
Spreadsheets can be used, with, for example, the application of ‘what-if’ and ‘goal seek’ facilities, to determine
the possible outcomes of different financial decisions. The display of financial data in a visual form can be
easier to understand. Data mining of sales data can show which goods or services contribute most or least to the
business’s profits.
2
The prices and availability of stocks, shares and goods from all around the world can be tracked and shown to
traders in real time. The prices of stocks and shares can be automatically tracked and bought or sold at predetermined prices. This is much faster than can be carried out by human traders. Alerts can be sent if trading
prices or the numbers of trades exceeds set limits. Trends and patterns in trading can be determined using data
mining.
Activity 12s
The teacher is not physically present with the student but is contacted if there are urgent questions that the student
needs answering, so immediate feedback is not possible. The learning by the student may be adversely affected if
there is a delay in the teacher’s response.
Activity 12t
The tutorial can be taken at any time and from anywhere with an internet connection, so the student has control of
when the tutorial is taken. Students can work at their own pace so can control their own progress through the tutorial.
Activity 12u
1
Using a CD-ROM does not require access to the internet. CD-ROMs are robust so can be used in workshop
environments.
2
Networked courses can be made accessible to employees and not to the public. Closer control is possible over
what is available and how and when it is presented as the course is restricted to the company network.
Activity 12v
Any two from:
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Teachers and students need access to a reliable internet connection with sufficient bandwidth to carry the video
and audio data. An unreliable internet connection will disadvantage students because they will miss out on the
teaching.
Technical problems may make the experience less satisfactory, for example video and audio may become out of
synchronisation and disrupt the lesson.
The teacher and student are not physically present together. This will reduce the interaction between them and
may allow students to become distracted or demotivated in lessons.
The teacher may find it more difficult to monitor and assess individual students during lessons.
Activity 12w
Any two from:
Teachers and students can be geographically separated and still have lessons.
Students and teachers can interact with others from all around the world to enhance their experiences of other
cultures.
Lessons can be recorded and reviewed at another date to reinforce learning.
Students who are unable to attend school in person can be included in lessons and so keep up with their studies
in line with other students.
Practice questions
1
Governments cannot regulate or control cryptocurrencies (1) because they are not centralised (1). Unregulated
currencies can create money (1) in an unpredictable and irresponsible manner (1), which can undermine the
value of the real money (1). Undermining the value of a currency can lead to price rises and inflation (1).
2
There is no need to place any trust in the other parties involved, for example the seller (1), because the large
amount of money involved (1) can be placed with a third party in an escrow account (1). This account can be set
up to automatically pay out to the seller (1) only when the painting has been delivered to the buyer (1) and
cannot be taken back by the seller (1).
3
Dealers and the other people involved in the use of cryptocurrencies are anonymous (1) so cannot be traced or
have their credentials checked (1). Because of the anonymity, incorrectly addressed payments cannot be
recovered (1) and the recipients of incorrectly addressed payments cannot be forced to repay them (1). Losing
the access key (1) means that the cryptocurrency is lost and cannot be retrieved (1).
4
There are no regulations governing how (1) or for what reason the data is being mined (1). People do not have
the opportunity to give or withhold their consent to the use of their data (1), as required by data protection laws
(1). People do not know what their data is being used for (1) or who will have access to it (1).
5
A traditional diary is handwritten and cannot be easily and clearly edited or corrected for errors (1), and it can be
lost along the way (1). A blog can reach many people at once (1) and is available to viewers at any time (1).
Blogs can be updated regularly and allow viewers to follow the progress of the student (1). Blogs can contain
images and videos, whereas a traditional, handwritten hardcopy diary cannot (1). Viewers may add comments or
suggestions to a blog but not to a traditional diary (1). A blog can be created and updated from a mobile device
(1).
6
Chat rooms can be set up to include only those who are invited so are private (1) and can be used for their own
employees to discuss developments and ideas (1). Customers can be invited to discuss new products in real time
(1), so providing instant feedback on their new product (1). Customers and employees don’t have to move from
their current task (1) so discussions can be carried on with less disruption to their work (1). Text-only chat
rooms do not provide non-verbal feedback (1) and there is often little control over the content of the text that is
posted, so inappropriate comments may be made (1). There is a possibility of malware (1) being transmitted as
chat rooms are not set up with security in mind.
7
SMTP (1) is used to send the email to the email server (1) of the recipient. The server determines the domain to
which the email has to be sent (1) and sends it over the internet to the domain’s email server (1). The recipient
Cambridge International A Level Information Technology © Brian Gillinder / Hodder & Stoughton Ltd
server receives the email (1) and determines the user from the local address of the email (1). It places the email
in the inbox of the recipient (1), where it waits until collected by the recipient’s smartphone using IMAP (1).
8
Teachers are required to learn new skills that allow them to use computing devices and IT software (1) and to
prepare materials for use on computers (1). Teachers customise their lessons or materials more for individuals
than for whole classes (1). Teachers guide and teach learners how to find and use information (1) and to verify
the information that is found (1), rather than to learn vast amounts of facts given out by the teacher. Individual
learning means that teachers can give each learner more help than in traditional classroom teaching (1).
9
Voice control can be used while carrying out manual tasks so there is no need to stop or wash hands (1) when
giving commands. Natural language can be used (1) and there is no need to remember long, precise commands
(1) or to type precise instructions (1). Remote-control devices are no longer required (1).
Voice-controlled devices are always listening and audio may be sent to central servers for interpretation (1) so may
capture personal and confidential information (1). This can be accessed by third parties and may be used for
fraud or blackmail (1).
10
Students do not regularly meet teachers in person (1) so receive less feedback (1) and may become less
motivated to complete tasks (1). Visual and computer-based materials can be stimulating aids that enhance
engagement (1) in lessons and the motivation of students. Students can work at their own pace (1) and repeat
topics as and when they wish (1), which reduces pressure from their peers to keep up (1). Students working
alone may lack the self-motivation to complete the tasks (1).
11
The initial costs of the equipment and software, and their on-going maintenance costs, are high to provide CBT
lessons (1). The production of good quality materials for CBT can be expensive in terms of software and storage
systems (1) and the time taken for teachers to prepare them is high (1). Customising lessons for individual
students requires teachers to learn new skills (1) and they may have to be trained, which will cost money (1).
Specialist technicians may need to be employed to maintain the software and equipment (1) and these can be
expensive.
Cambridge International A Level Information Technology © Brian Gillinder / Hodder & Stoughton Ltd
13
New and emerging technologies
Activity 13a
1
Floors are usually flat and horizontal so the structure has a low centre of gravity to avoid tipping over. It also has
fittings for sensors and power sockets for recharging. The robot that cleans windows needs a structure that
distributes the weight of the components around it, and it does not need a power socket as it is likely to have a
fixed power line. It does not need sensors to locate itself around a floor but only to determine the window size.
2
The AI needs to determine its position in relation to objects on the floor or in its way. It needs to determine
whether or not its waste storage is full and if the on-board cleaning materials (if any) are adequate or need
refilling. Also, the status of its batteries has to be monitored and the time remaining before it needs a recharge
has to be calculated. The AI needs to determine the shortest distance to the power-charging socket and the
process of connecting each time.
Activity 13b
1
The human shape is not suited to any specific task but is able to carry out many different tasks. Such as shape
would be wasteful of resources to design, create, maintain and operate for a single, specific task.
2
Many humans find humanoid robots disturbing and cannot relate to them. They may prefer to discuss matters
with real humans.
Activity 13c
1
Sidewalks, pavements and roads are already crowded with pedestrians or other vehicles and may not be wide
enough. People will have to take avoiding action and may put themselves in more danger, for example stepping
off a sidewalk into traffic. Unexpected hazards such as road or highway maintenance may not appear on the
navigation maps used by the drones. Drones that have been disabled by malfunctions or accidents will cause
further hazards.
2
They can be used instead of staff to deliver medicines to patients on set schedules. They can operate
continuously, for example to resupply bedding and other goods to rooms or storage areas.
Activity 13d
1
Machine translation has no human input.
2
CAT has human input so can take into account the dialects and unusual spellings found in old documents.
Machine translation may translate out of context and so change the meaning of the text.
Activity 13e
1
Local cultures have different rules on what is acceptable and what is not, so wordings must reflect this.
2
One from:
Dress code in the images
Expressions on the faces of characters
Hand gestures by the characters.
Activity 13f
The original hologram needs specialised and expensive laser-based equipment to create. The holograms are too
complex to recreate cheaply so there is no profit to be made from the counterfeiting.
Activity 13g
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Sunlight contains ultraviolet light, which can erase the rewritable discs because it affects the polymers used to store
data. Commercial discs are manufactured by pressing techniques and do not use the polymers so are not affected.
Activity 13h
Additive manufacturing deposits layers of material on to other layers and builds up the structure, whereas subtractive
manufacturing removes, drills out or cuts off material, to leave the structure shape behind.
Activity 13i
For home printing, the components would have to be supplied to home users in bulk, which would mean that they
could be stolen or misused. There is less control over the dosage and construction of the drugs so patients could be at
risk.
Activity 13j
1
These are some of the technologies used:
Smartglasses are made by 3D printing to produce the complex shapes in one solid object, without joins.
Smartglasses may use Wi-Fi, 4G or 5G connections to a central assistance centre or to search for
information about the local area or environment.
The internal operations of the smartglasses may use Bluetooth® connections to a smartphone or retinal
implants to access the internet.
2
These are typical uses by tourists:
Smartglasses can access the internet to gather information about an area and display it as an overlay on
tourist attractions.
Smartglasses can aid in navigation of areas and can be connected to a smartphone for uploading images
and commentary in real time to social media.
Activity 13k
1
A device has to be worn on the body, like a watch or smartglasses, to qualify as ‘wearable’. Being carried, for
example inside a coat worn on the body, is not enough.
2
A smartwatch uses sensors that detect physical parameters such as heart rate. The data from the sensors is either
recorded or sent to other devices, for instance using Bluetooth, for later analysis. A smartwatch is very portable
so can be worn without hindering the athlete. The data can be compared over time to indicate how the athlete
can adjust their training to improve performance.
Activity 13l
Use of Bluetooth to connect over short distances, for example to a smartphone.
Use of 5G to connect to mobile communications systems, for example mobile/cell phone systems.
Use of USB connections, for example to a laptop.
Activity 13m
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Use of AI requires a great deal of processing power.
Need for vast amounts of data storage.
May make use of holographic or 4G storage systems.
Need for high-speed communications systems.
These are needed to analyse vast quantities of data.
Practice questions
1
Social-media posts are analysed by AI to extract data, for example about likes (1), names of brands mentioned
(1) and viewing history (1). These are matched (1) to advertisers or to companies’ products and advertisements,
and these are inserted into news feeds and listings that users look at (1).
2
Augmented reality allows the clothes to be overlaid (1) on the person and viewed on a tablet or smartphone (1).
The sizes are adjusted automatically by the AR system to suit the shopper (1), who can also try different colours
and styles (1). There is no need to keep visiting the changing rooms, to change clothes in a public area or to
allow others to see the results (1). The AR can be used to show the clothes in different scenarios (1).
3
The robotic device cannot be fully automated or autonomous as, currently, AI is not sufficiently developed (1).
A remote surgeon is in control but is dependent upon the images from the devices (1), which are not as good as
the human eye at ‘taking in’ all the details (1). The network delay (latency) means that very precise actions or
movements may be slightly delayed and the feedback to the surgeon is slow (1). Any actions in the case of
emergencies (1) or unexpected problems are difficult to deal with (1).
4
In answering this question, there are two main aspects to be considered. There is the impact on the patient and
the impact on the health care givers, such as doctors, surgeons and nurses. Also, positive and negative impacts
must be included.
Impacts on the patients include:
Continual monitoring of body parameters even when discharged/not in a hospital (1) so health can be
checked over time by doctors (1).
Health can be checked remotely by doctors (1) so they are alerted to problems more quickly (1).
Patients have to wear the device all the time (1) and this can be difficult or uncomfortable for some (1).
Impacts on the health care providers include:
Can collect more data about patients’ conditions/physical parameters (1) so have more understanding of
the patients’ condition and can provide better care (1).
Can monitor patients while they are away from the health centre/hospital (1), which frees up space for
other patients (1).
Doctors do not have to monitor patients as this can be done by support staff (1), so doctors can treat more
urgent cases (1).
Have more data to analyse and understand (1), which can take more time away from patient care (1).
Heath care facilities monitor many devices (1) so require more computing facilities (1), which can add to
their costs (1).
5
Both benefits and drawbacks must be included in a good answer.
Some benefits are:
Robotic devices can perform repetitive tasks (1) for long periods of time without a deterioration in
performance (1), unlike humans.
Robotic devices can work continuously without breaks (1) apart from routine maintenance (1).
Production lines do not stop for shift changes of workers (1) because robotic devices only need
monitoring by technicians (1).
Overall production costs are lower than when many manual workers are employed (1), even though the
running costs and maintenance of robotic devices is high (1).
Customised automobiles can be produced (1) with unique features/colours (1) for individual customers
because the production line robots can be programmed to pick/assemble specific parts or use different
paint colours (1) on a per vehicle basis (1).
Some drawbacks are:
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Robotic devices need maintenance and replacement of parts (1), which can mean that specialised
technicians are required (1). These are individually more expensive than manual workers (1) and require
special, expensive training (1).
Robotic devices need a constant supply of raw materials (1) and if this is interrupted by supply problems
(1) they cannot produce anything because the devices can (usually) only perform single tasks without
reprogramming (1).
Robotic devices cannot respond to sudden changes (1) because they need reprogramming to handle any
alterations in the task (1).
6
Both benefits and drawbacks must be included in a good answer.
Some benefits are:
Instruction manuals can be automatically made available in different languages (1).
Manuals can be automatically translated if not immediately available (1) in the required language for a
region (1).
Different regional dialects can be catered for (1) without having to completely translate the manual over
again (1).
Some drawbacks are:
Instruction manuals contain technical language (1), which must be checked by humans (1). This adds to
the time and cost of their creation (1).
Humans must check that the translated instructions are safe to use (1) and do not contain errors that
might result in damage to the TV set or the user (1). This adds to the cost of production (1).
Instruction manuals contain technical language, which may need individual translation as the terms may
not exist in language databases (1).
7
The answer to this question should include both positive and negative impacts.
Some positive impacts are:
Counterfeiting can be reduced (1) because holographic images are difficult and expensive for forgers to
recreate (1).
Customers can be reassured that products carrying a holographic label are genuine (1) so they will buy
only genuine products (1).
Holographic imaging in presentations can attract investors (1) because it is innovative (1).
Advertising presentations at commercial events can use objects and designs without having to physically
move them to the event (1), which is cheaper than transporting them (1).
Holographic images on business cards can store more information than traditional business cards (1).
Some negative impacts are:
Objects for sale cannot be physically handled or examined (1) and colours may not be easy to recreate as
holograms (1) so sales may be lower (1).
The lighting conditions needed for reproducing holographic images of objects can be difficult to recreate
in marketing venues (1).
The cost of producing and printing holographic images can be prohibitive for small companies (1).
8
These are some suggested answers:
Not all materials from computing devices, for example plastic cases, can be recycled (1) so these have to
be burnt or put into landfill (1).
Burning plastics can generate dangerous compounds (1) that can leak into the atmosphere (1) or water
supplies (1).
Components such as plastics do not degrade quickly (1) so pose a threat to wildlife and ecosystems for a
long time (1).
Components dumped in landfill can leak dangerous chemicals or rare metals into the ground (1) and
these can poison crops and people (1).
Dangerous metals and compounds leaked into the ground can enter the food chain (1) and become
concentrated in the food we eat (1).
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14
Communications technology
Activity 14a
1
Three from:
Data transfer speeds over LANs are (usually) higher than those over WANs.
LANs use devices such as switches and bridges that work at layer 2 of the TCP/IP model, whereas
WANs use, for example, routers that work at layer 3.
LANs develop fewer faults/problems with devices than WANs because LANs have fewer devices.
LANs have fewer data transmission errors than WANs because WANs use a large number of
connections over public telecommunications systems.
A LAN is usually owned and maintained by a single organisation whereas a WAN may use systems
owned by many different organisations.
LANs are cheaper to maintain and upgrade than WANs because the devices are in a relatively small area
compared to those in WANs.
2
LANs use these protocols:
Ethernet (strictly speaking, this is a technology)
Wi-Fi (strictly speaking, this is a technology)
TCP/IP
Protocols for specific services, for example HTTP, HTTPS, FTP, IMAP, SMTP, Telnet, etc.
3
WANs use these protocols:
High-level Data Link Control (HDLC)
Point-to-Point Protocol (PPP)
Frame relay.
Activity 14b
There is no central storage of resources such as files so there is no easy way to locate specific resources. The network
can become very busy/overloaded/congested with traffic when many nodes request resources from other nodes,
which reduces its performance and means that requests for resources often fail. No central control means that
administration is more difficult and nodes can join or leave at any time, which can disrupt the network for users.
Activity 14c
A VPN sets up a secure connection across the internet that uses public telecommunications systems. The VPN can be
set up to require authentication by the home user to protect the company network from unauthorised users and can
use encryption to protect the data being exchanged.
Activity 14d
There are several types of physical network topology used in LANs: bus, ring, star, tree, mesh and hybrid. You
should sketch each one and against each add notes about its structure and advantages and disadvantages over the
others. Suitable resources include:
Network Topology: 6 Network Topologies Explained & Compared (www.comparitech.com)
Types of Network Topology (www.geeksforgeeks.org)
Activity 14e
A Wi-Fi extender picks up wireless signals from a WAP and re-broadcasts the signals on different frequencies,
whereas a WAP has a wired connection into a network and provides wireless access to the network.
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Activity 14f
Company LAN to internet
Two sections of a small LAN in a company
Two separate sections of a company LAN
Activity 14g
Streamed movies (video and audio) are sent in packets across the internet. The packets take different routes to reach
the viewer so arrive at different times and, sometimes, out of order. Buffering allows the movie application to collect
the packets quicker than it shows them to the viewer, giving time to reorder the packets and gather ones that may
have gone missing. The viewer is able to watch the movie without interruption.
Activity 14h
Servers provide services such as email, network security, and file and document storage to the company’s employees.
Servers enable the administration of network resources and security to be centralised.
Activity 14i
NAS is network-attached storage, which means that storage devices such as hard disks are connected to a network
and can only be accessed remotely.
Activity 14j
Many virtual servers can be run on one physical server, reducing the use of physical space. The use of virtual servers
allows the hardware to be upgraded more easily without service interruption as multiple instances of the server can be
run and use can be easily switched between servers if one set of hardware is switched off.
Activity 14k
Co-axial cable needs no special skills or tools and so is cheap to install and maintain. It is less susceptible to electrical
interference and cross-talk than twisted pair cables so data is transferred reliably.
Activity 14l
1
Telnet is not secure and gives almost total access to control of the devices.
2
HTTPS is often used. Most devices have a built-in web server for their administration and this requires login
from a web browser with access to the configurations options.
Task 14a
1
Pinging www.google.com and google.com produces different IP addresses. The IP address of these is also
subject to change. At the time of writing, www.google.com was 172.217.168.14 and google.com was
142.250.179.228. Note that Google could consider repeated pings to be a nuisance.
2
The exact response returned by tracert will depend on your computer and your location.
3
Some hops in tracert are shown as stars because the router has not responded to the pings within the time limit.
The first ping sets the time-to-live (TTL) to 1. When the first router receives the ping, it reduces the TTL by 1,
and because the new TTL is 0 it returns an error with its IP address in an ICMP message. Tracert repeats the
ping, this time with a TTL of 2. Router 1 reduces the TTL by 1, and forwards to router 2. Router 2 reduces the
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TTL and, because it is now 0, returns its IP address. This process is repeated until either the final destination is
reached or the maximum allowed TTL is reached. If no answer is heard from a ping, tracert displays the *.
Task 14b
A typical arp display is:
This will have a list of addresses shown below in columns. The first column is the IP address, the second column the
MAC address associated with the IP address, and the last column the status of the IP address. Dynamic addresses are
assigned by a DHCP server when the host, in this case a laptop, starts up and may change, while the static ones are
fixed.
Activity 14m
1
Most firewalls block connections that originate from outside the network, so active mode FTP is blocked
because the server sets up the data connection. Firewalls can be configured to block the ports that FTP uses.
2
There is no need to set up an account and usernames and passwords are not required for access.
Activity 14n
1
Unlike TCP, UDP does not provide error management or acknowledgment of packets as it is more important for
packets to continually arrive than for missing ones to be requested again. The loss of a few packets in a video or
audio stream goes unnoticed so the overheads of checking packets are not required.
2
Some uses of UDP are:
The Domain Name System (DNS) used for looking up addresses.
The Dynamic Host Configuration Protocol (DHCP) for assigning network addresses.
The Routing Information Protocol for distributing routing data between routers.
The Simple Network Management Protocol (SNMP) for managing devices such as routers on a network.
Activity 14o
1
The network address is different; one is 192.168.12 and the other is 192.168.14, which means that they are on
logically different networks so cannot communicate.
2
One of these options:
A router could be used to direct network traffic between the two networks.
The network address of one laptop could be changed to the same network address as the other.
Task 14c
The displayed details and the format of the tables will depend upon the specific computer. A typical output from the
command will include a list of the interfaces, and an IPv4 and IPv6 route table. Any fixed routes may also be shown.
Activity 14p
1
The best route would be network A to router 1 to router 4 to network B.
2
The metric would be 2 because there are two routers on the path.
3
The route chosen by RIP does not take bandwidth, for example, into account. Router 4 may be on a lowbandwidth connection, so a better, faster route could be via routers 2 and 3 if they are on high-bandwidth
communication systems.
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Activity 14q
1
It is easier to visualise and understand if the model layers are represented as being in a stack.
2
The services provided by each set of protocols can be grouped by function. Each function can be
altered/amended/changed without affecting the other sets of functions.
3
Conceptual models organise the protocols by features and functions and help to show how they work together.
Activity 14r
4G provides greater bandwidth and this allows more data to be transferred in a given time, so the video can be in
higher resolution or HD without freezing or jerky motion.
Activity 14s
Low latency means minimal delay in the exchange of data so commands and responses are almost in real time.
Activity 14t
A satellite in geosynchronous orbit has an orbital period (the time taken to orbit the Earth) that is exactly the same as
the time taken for the Earth to turn once on its axis, which is 23 hours, 56 minutes and 4 seconds. Seen from the
Earth’s surface, the satellite will return to precisely the same location in the sky after one day. The inclination (tilt)
and eccentricity (deviation from a perfect circle) determine whether or not the satellite remains still in the sky or
appears to move on a figure-of-eight path.
A geostationary orbit is a special case of a geosynchronous orbit where the satellite is in orbit over the equator of the
Earth (the Earth’s equatorial plane) and should appear to remain in exactly the same position all the time. In practice,
due the Earth not being a perfect sphere and due to the gravitational effects of other celestial objects, satellites in a
geostationary orbit may still appear to move slightly over time, so they carry small amounts of thruster fuel to allow
them to keep their position. Ground stations can move their antennae to keep focused on the satellite.
Activity 14u
1
Communication is by microwave links, which travel in straight lines and are blocked by obstacles such as hills
or buildings.
2
Rain clouds can absorb satellite TV signals and reduce the signal strength to below the usable level so the TV
data is not received.
Activity 14v
A suitable table would be:
Fingerprint
recognition
Medium
High
Medium
High
High
Facial recognition
Low
High
Medium
Medium
Medium
Iris patterns
High
Medium
Low
Medium
High
Retinal patterns
High
Low
Low
High
High
Voice recognition
Low
Low
High
Medium
Medium
Keystroke patterns
Low
High
High
Low
Low
Handwritten
signature
recognition
Medium
Medium
Medium
Medium
Medium
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Activity 14w
1
A threat is any factor that is not under the control of the owner, administrator or users of the system and that has
an adverse, or negative, effect on the system.
2
Physical threats include:
Vandalism of equipment/devices preventing them from functioning.
Theft of devices resulting in the loss of services/function.
Fire or flood damage preventing an IT system from functioning.
Electrical disturbances, such as power loss or fluctuations, causing component damage.
Practice questions
1
Advantages include the sharing of peripherals such as printers (1) between the many devices and having control
of the printing (1), so it can restrict what is printed, the number of printouts and who is allowed to print (1).
However, if the printers are some distance from the user (1), others may see the printouts before the user collects
them (1) and this reduces the security of documents (1).
Document storage can be centralised (1) on a file server (1). This increases security (1), makes updating the
documents easier (1) and makes them available to all company users (1). House styles are easier to enforce with
centralisation of documents (1). Backups can be centrally organised and maintained (1). Emails can be sent and
access to the internet can be controlled with mail and proxy servers (1). A single internet access can be shared
and controlled with firewalls (1), DMZs and proxy servers. Since storage and devices can be accessed remotely
(1), security can be administered and monitored centrally, but setting up and monitoring the security of data can
be more difficult.
2
A network policy should cover these aspects:
Access and security (1) to control what users and devices can and cannot access and do (1).
Define what applications can be used (1), what they can access on the network (1) and how important
they are on the network (1).
How network traffic should flow/be routed (1).
How the policies should be implemented/enforced (1).
3
a
b
4
Marks could be awarded for ease of use, for example:
The use of NFC systems does not require any extensive training (1) since all that is needed is a tap by a
smartphone/device (1).
Marks could be awarded for valid examples, such as:
NFC-enabled tags worn by nurses/doctors (1) can pick up data from and identify a patient (1) using a
similar tag on the patient (1).
Access to patient records is faster (1), reducing consultation times (1).
5
Marks could be awarded for:
The web browser on the laptop sends a request (1) to the web server (1). The web server and web browser send
each other requests and responses with authentication details (1). The web browser requests the required pages
(1) and the server responds with the relevant pages/content (1). This is repeated (1) until the browser has all the
information required to display the pages (1).
6
a
b
To provide the rules (1) to enable them to exchange data (1).
Reliable protocols send a message to notify the sender whether or not data packets have arrived (1), but
unreliable protocols do not (1).
Up to 6 marks may be awarded from:
WANs usually cover large geographical areas (1), whereas LANs are usually restricted to a few buildings
or to a campus (1). WANs make use of public telecommunications systems (1) whereas LANs do not
usually do so (1). WANs use different protocols from LANs (1) to allow network traffic to travel over
different types of communication media (1). A WAN may be made up of numerous LANs (1).
Up to 6 marks may be awarded from:
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There are more nodes on WANs (1) so there is more opportunity for unauthorised users to intercept the
data (1). Data on LANs can be protected from unauthorised users (1) by firewalls or other security systems
(1).
7
Three from:
An email client and an email server (1)
A web browser and a web server (1)
A laptop printing from a word processor to a networked printer (1)
A smartphone posting photographs to a social-media platform (1).
8
a
b
9
a
b
10
Two from:
Static routing tables require time and expertise to set up (1).
Small errors in static routing tables can cause immense disruption to networks (1).
Any network congestion/problems/node failures are not automatically dealt with (1).
Two from:
No control over the route taken by packets across the networks (1).
Network traffic/congestion can be increased because routers exchange information (1).
Network latency can be increased because each router has additional computation to carry out to
determine the best route to use (1).
The address must be unique so as to identify only one device on the network (1), else IP packets cannot be
sent to/from the laptop (1).
Ways that an IP address could be assigned to the laptop are:
Manually assigned by the user (1).
Assigned by DHCP from a DHCP server when it joins the network (1).
A script kiddie is an unskilled individual (1) who writes scripts and program code, or uses other
people’s scripts or codes, to attack computer networks and systems (1).
ii A cracker is a person who gains access to networks/applications by taking advantage of security flaws
(1). Crackers often do not have the skills to create their own software applications (1).
b
Each type of perpetrator has different skills and methods of attack (1) so resources can be directed at these
if the perpetrator type is known (1).
a i
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15
Project management: answers
Activity 15a
1
The project objectives are the deliverables, which are: the product to be constructed, the time taken by the
project (duration), the measures of success of the project, and the project documentation.
2
Objectives are decided during the initiation stage.
Activity 15b
1
SMART objectives are Specific, Measurable, Achievable, Realistic and Time-sensitive (or alternatively
Specific/Strategic, Measurable, Attainable, Relevant/Resourced and Time-limited).
2
A deadline is the time at which a project, stage or task must be completed.
Activity 15c
1
Project creep is the addition of extra features or user requirements as the project proceeds, which were not
included in the original planning.
2
Poor management or poor communications between stakeholders and team, so that decisions are not made in
time or do not take into account the project constraints.
Activity 15d
Testing the game
Fourth
Writing the test report
Fifth
Designing the game
Second
Writing the user guide
Sixth
Coding the game
Third
Writing the test report
Seventh
Releasing the game
Last
Planning the project
First
Activity 15e
1
Information overload can produce poor decision-making because all the information is not understood or seen.
Team members may become demotivated because they receive too much irrelevant information and do not have
time to read or understand it, which may also affect their decision-making. Too much information can prevent
team members from achieving their goals and objectives.
2
Ways to reduce information overload include:
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Group-related tasks
Prioritising tasks
Completing smaller tasks first
Avoiding multi-tasking
Turning off unnecessary alerts
Filtering emails
Checking emails less frequently.
Activity 15f
1
The diary can be accessed from anywhere using the internet so can be used on a desktop, laptop or mobile
device. Diaries can be shared between the manager and team members and appointments and meetings
scheduled more easily. Reminders and alerts can be sent automatically to those involved. Schedules can be rearranged automatically if changes are required and everyone can be alerted to the changes.
2
The diary must be kept up to date and all changes or appointments logged and read, and this can take up
valuable time. Sharing requires all users to be online and updating the diaries regularly. Too many alerts may
lead to information overload and important appointments may be missed. The privacy settings must be
configured accurately to avoid loss of privacy or confidential meetings being alerted to everyone.
Activity 15g
1
A possible chart would be:
2
A Gannt chart shows the chart visually, making it easier to understand which tasks are dependent on each other
and which can be carried out concurrently.
3
Task 6 is concurrent with tasks 3 and 4.
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Activity 15h
1
A chart could be as in the sketch. The Start and End points are not always required.
2
Student’s own answers.
3
The critical path has a duration of 1 + 3 + 4 + 4 + 4 + 6 + 5 days, which is 27 days.
Activity 15i
1
A suitable PERT chart with the total and free floats is shown below.
2
The critical path is tasks 1 4
7
6
5
9
12.
Practice questions
1
Project scoping involves gathering as much information (1) as possible about the objectives (1) and what needs
to be done to meet them (1). The type of work (1), the methods to be used (1) and who will do the work (1) are
researched and documented (1). The project risks (1) and constraints (1) are analysed and documented. The
costings and budget (1) are also included in a scope.
2
Acceptance criteria help the project manager to decide when a project is finished (1) because they state what
must be complete to consider the project over (1). Everyone involved in the project (including the project
manager, the team members and the stakeholders (1)) is satisfied and agreed (1) that the project is over when the
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acceptance criteria are met. There is no room of interpretation if the acceptance criteria are clear (1) so there are
no arguments about the end of the project (1).
3
a
b
Total float is the time that a task can be delayed (1) without affecting the duration (1) of the whole project
(1). Free float is the time that an individual (1) task can be delayed without affecting the early start (1) of its
successor task(s) (1).
Tasks on the critical path must have a total float of zero (0) because any delay at all (1) of any task on the
critical path will delay the completion of the whole project (1) by the same amount of time as the task delay
(1).
4
PMS has features that can allow collaboration with team members in real time (1) so that everyone is kept up to
date with the project (1). Documents can be shared (1) so that important project documentation is seen and can
be edited by all (1). Costs can be managed and resources allocated and re-allocated as necessary during the
project (1). Risks and constraints can be managed and their effects monitored throughout the project (1). Reports
can be generated (1) and automatically sent to selected team members as required (1). Links to diary software
can alert managers and team members to upcoming milestones, overruns or other project events (1).
However, the use of PMS can be expensive and may not be economical for smaller projects (1). Small projects
may become more complex if using PMS and may take much longer (1). There is a risk of information overload
or too many alerts and these can delay or distract team members from actual work on their tasks (1).
5
Using the CPM can take a lot of time and effort (1) and in very large projects there may be several critical paths,
which makes understanding the whole project difficult (1). In large, complex projects, where PMS shows several
critical paths, choosing which is ‘most’ critical is not easy and usually has to be carried out manually (1). Task
durations may not always be accurate and there is no allowance for this or for errors in CPM (1). Changes to the
PERT chart or network diagram during the project (1) mean that the critical path may change and the CPM
calculations have to be redone (1).
6
A chart could be as in the sketch.
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16
System life cycle
Activity 16a
1
Each stage depends on the results or deliverables from the previous stage, and the last (maintenance) stage is
used to refine the specifications/designs to make improvements to the product, which has to go through the
process again.
2
A smartphone consists of many components that work together to take in data, process it and output information
for a user.
3
An air traffic control system comprises all the hardware including radar, sensors on the ground, runway lighting
and indicators, computer software, and people who use the system. For example:
The computer hardware in the control towers
The software for monitoring the air and ground traffic
The sensors and systems that gather data from around the airport runways, taxi-ways and gate areas
The local and remote radar systems that supply data to the computer systems
The radio equipment and the software for using it for communications between the aircraft and the
controllers and other services on/in the airport and central air traffic control
The air traffic controllers who use the systems
The support personnel who carry out administrative and other tasks.
Activity 16b
1
A feasibility study determines whether or not the project can be done by the company, for example whether it
has the skills, personnel and resources to carry it out, whether it is financially worth the investment and can be
completed on time.
2
The analysis stage provides the information about the current system that is used as a basis for the planning and
designs of the new system. It discovers the problems with the current system and enables the creation of the
specifications needed to create the replacement.
Activity 16c
Customers who eat at a restaurant
Workers in a factory assembling
computer monitors
Managers in a bank
End users of an accounting
system
Delivery drivers of a parceldelivery service
Designers of a new set of system
reports
Borrowers of books from a
library
Activity 16d
It contains the details of what the client who is asking for the new system wants it to be able to do. Without it, the
developers would not know what features and functions to include.
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Activity 16e
1
Documents would be printed at the end of the rental process. Use the symbol that indicates a multi-page
document or more than one document:
These represent the rental agreements and documents that it is necessary for the driver to carry with the car.
They would appear here:
Documents could also be produced as a printed list to display the cars available for the customer.
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2
The system should check if the user has an account. If not, as is the case here (it’s a new user), the account has
to be created, and then the username and password have to be checked to allow login.
An example flowchart could be as shown.
Activity 16f
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Activity 16g
1
A format check can be applied to ensure that it has two parts separated by an @ symbol.
2
Validation checks only that the email address conforms to the correct format. It does not/cannot check that it is
accurate/right. Entering the email address twice allows the computer to check by comparing the two entries that
the user has entered an accurate address because it is unlikely that a user will make the same mistake twice and
it allows the computer to check to see whether or not the user has made spelling errors.
Activity 16h
1
Three text fields should be used that only allow numbers and that check the range of values. Because the values
of 2 m and 2 mm use different unit scales, sometimes forms ask that all values be input as mm or convert them
to mm before submitting them.
2
a
b
c
Any value from 0 up to 2000 mm would be valid or normal. In practice, in this example, the doors are
unlikely to be very small, but 0 to 2000 would be a sensible range. The validation routine could be set as >0
and <2001, which allows values from 1 to 2000.
Extreme data is still valid data and examples would be 1 or 2 and 1999 or 2000. Strict interpretation of
extreme data would be 1 and 2000.
Abnormal data would be any value outside the range of 1 to 2000 mm, e.g. 0 or 2001.
Activity 16i
1
When replacing a stock control system in a supermarket, parallel running would be the best choice because there
is a need to check that the new system accurately monitors the stock by comparing the outputs with those of the
current system.
2
When replacing the user accounts system of an online bookshop, parallel running would be the best choice to
ensure that the user accounts are managed correctly. By comparing the account details and their management,
the shop owners can be sure that the details are safe, secure and accurate.
3
Changing from local, hard disk storage of company documents to cloud-based storage should be carried out by
direct changeover. All the documents must be in the same place and be immediately accessible after the change.
4
Replacing the workflow system for taking and fulfilling orders in a mobile (cell) phone store should be done by
direct changeover so that all the workers are following the same pattern of work.
5
Replacing the booking system for rail tickets in a travel company with many branches should be done by pilot
implementation because each branch can be changed over without the others. This allows the users to be trained
and to try out the new system and for any problems to be fixed before the other branches change over.
6
Replacing the operating systems of desktop computers in the offices of a multinational company should be done
by phased implementation. Introducing the new OS in some offices before others allows problems to be fixed
and users to be trained in stages.
7
Replacing the manual counter services in the branches of a bank with automatic teller machines in the foyer
should be done by pilot implementation so that the new system can be tried out, for example for customer
acceptance, problems and training, before fully replacing counter services.
8
Installing 5G mobile services in cities would use pilot implementation is some areas to determine whether or not
the system is viable, economic and technically possible.
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Activity 16j
1
It is corrective maintenance.
2
The steps are:
Diagnose the problem by seeing the problem as it occurs.
Locate the cause of the error by testing the app’s code.
Amend the code.
Test the code.
Test the app on smartphones to see if it works correctly.
Ask end users to test the app.
Record the tests, results and outcomes for the client/owner and developers of the app.
Activity 16k
Adaptive maintenance corrects errors or problems that occur when new hardware is installed, when an OS is updated,
or when changes have to be made to meet new regulations. Perfective maintenance is carried out to improve the
system so that end users experience more features or better performance from it.
Activity 16l
1
A gaming app may have many different component parts, such as user interfaces for login and for gaming, a
game engine, a score table and a facility for online gaming, which could be developed and tested simultaneously
and brought together near completion time. A note-taking app would be much simpler and a rough prototype
could be made, tested and discarded and the next prototype made quickly.
2
There must continual, frequent communications between the developers and clients so that the process can be
fast. Prototypes must be tested and feedback quickly given by the client so that developers can start on the next
prototype as soon as possible to amend or add features/functions. This process is iterative so, to keep the
timescales small, communications must be good.
Practice questions
1
A suitable DFD could be:
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