The TCP/IP protocol may be viewed as a stack that contains four layers: Application, Transport, Internet, Link. Describe how the layers of the TCP/IP protocol stack interact with each other. [4]

One mark per mark point (Max 4) MP1 Each layer can only accept input from the next higher layer or the next lower layer MP2 There is an interface between the adjacent layers which is the only interaction between layers MP3 Data is added to the headers as the frames/packets pass through the layers MP4 The interactions are carried out by installed software MP5 User interaction takes place at the highest/Application layer of the stack through protocols associated with that layer of the stack MP6 Direct access to hardware takes place at the lowest/Link layer of the stack

(a) The Internet layer and Link layer are two layers of the TCP/IP protocol suite. Describe the purpose of the Internet layer and the purpose of the Link layer. [5]

One mark per mark point (Max 5) One mark per mark point for purpose of Internet Layer (Max 3) MP1 To identify the intended network and host. MP2 To add header containing IP addresses. // To address packets with their source and destination IP Addresses. MP3 To prepare packets for delivery by formatting them into datagrams. MP4 To route datagrams through the optimum route over a network. One mark per mark point for purpose of Link Layer (Max 3) MP5 To prepare the next hop by managing the link between two directly connected devices. // To identify and move traffic across local segments. MP6 To format datagrams into frames for transmission. MP7 To identify network protocols in the packet header. // To ensure correct network protocols are/is followed. MP8 To deliver frames to the receiving network. // To receive frames from the sending network. // To map IP addresses to MAC physical addresses. MP9 To provide error checking/error correction/recovery/reconstruction MP10 including resend requests.

(b) Describe the function of a router in packet switching. [4]

One mark for each correct marking point (Max 4) MP1 The router reads the IP address of the destination from the packet header. MP2 A router uses a routing table to find information … MP3 … about e.g., available hops / netmask / gateway used / adjacent routers / the status of the routers along the route. MP4 The router determines the next hop / optimum route. // The router sends the packet on its next hop. MP5 The router manages the hop counter // The hop counter is reduced by 1 every time the packet passes a router.

Secure Socket Layer (SSL) and Transport Layer Security (TLS) are two protocols. Explain how SSL/TLS is used when client-server communication is initiated. [4]

One mark for each correct marking point (Max 4) MP1 An SSL/TLS connection is initiated by an application/client. MP2 Every new session begins with a handshake as defined by the SSL/TLS protocols. MP3 The client requests the digital certificate from the server // The server sends the digital certificate to the client. MP4 The client verifies the server’s digital certificate MP5 … and obtains the server’s public key. MP6 The encryption algorithms are agreed. // The symmetric session keys are generated/defined. MP7 A secure session is established between client and server

Secure Socket Layer (SSL) and Transport Layer Security (TLS) are two protocols. (a) State two functions of SSL/TLS. [2]

One mark for each mark point (Max 2) MP1 Ensure security/privacy when using the internet MP2 Data encryption MP3 Identification / authentication of client and server

(b) Give two examples of situations where the use of SSL/TLS would be appropriate. [2]

One mark for each mark point (Max 2) MP1 When transmitting authentication data e.g. passwords, session cookies MP2 When transmitting data that must be protected from modification on its way to or from a server e.g. user input, or results from the server MP3 When transmitting data classified as non-public

(a) The Application Layer and Transport Layer are two layers of the TCP/IP protocol suite. Describe the purpose of the Application Layer and the purpose of the Transport Layer. [5] Purpose of Application Layer ..................................................................................................... Purpose of Transport Layer .....................................................................................................

One mark per mark point (Max 5) One mark per mark point for purpose of Application Layer (Max 3) MP1 To provide services / interface with the user // access to applications, for example login, file transfer, network file access, email, etc MP2 To provide mechanisms for securing communication e.g. encryption/authentication MP3 To define/provide protocols used to allow the exchange of data/communication // to contain programs that exchange data MP4 Error detection and recovery mechanisms to handle application specific errors One mark per mark point for purpose of Transport Layer (Max 3) MP5 To provide logical communication between applications running on different hosts // To ensure that data is delivered to the correct application process on the destination machine MP6 To ensure error-free, end-to-end delivery of data between a source and a destination, in sequence // to provide error recovery techniques such as error detection codes and automatic repeat request MP7 To break data into segments when sent and to reconstruct when received // To reassemble segments at destination MP8 To regulate network connections // to provide flow control mechanisms to prevent data loss

Sheila has a customer called Fred. Fred wants to send Sheila a confidential document as part of a transaction. Explain how Fred uses asymmetric encryption to send his document securely. [4]

One mark per mark point (Max 4) MP1 Sheila’s computer uses an algorithm to generate a matching pair of keys private and public MP2 Sheila’s computer sends Fred’s computer Sheila’s public key // Fred‘s computer acquires Sheila’s public key MP3 Fred’s computer encrypts the document/plain text using Sheila’s public key to create cipher text MP4 Fred’s computer sends the cipher text to Sheila’s computer The cipher text can only be decrypted using Sheila’s private key // Sheila’s computer uses Sheila’s private key to decrypt the cipher text

(a) Describe what is meant by a digital certificate. [3]

One mark per point (max 3) MP1 A digital certificate is an electronic/online document. MP2 used to authenticate/prove the identity of a website/the online identity of an individual/organisation MP3 typically issued by a CA MP4 For example: it contains information identifying a website owner/individual and a public key.

(b) Explain the role of a digital certificate in creating a digital signature. [2]

One mark per point (max 2) MP1 The digital certificate provides the public key MP2 … that can be used to validate the private key associated with the organisation/website/digital signature

The TCP/IP protocol suite has four layers: Transport, Application, Link, Internet (a) Complete the diagram to show the correct order for these layers. [2]

Application Transport Internet Link

(b) Describe the function of the Transport layer. [2]

One mark per mark point (Max 2) MP1 The transport layer is responsible for delivery of data from the source host to the destination host MP2 It is where data is broken up into packets and sent to the internet layer MP3 Adds the sequence number to the packet header MP4 It establishes end to end contact MP5 It ensures data arrives error free // It retransmits packets if lost

(c) Outline one protocol that is associated with the Application layer. [2]

One mark for name of protocol and one mark for expansion (Max 2) HTTP(S) – responsible for correct transfer of files / hypertext documents that make up web pages on the world wide web FTP – used when transferring files from a server to a client on a network POP3 – handles the receiving of emails IMAP – handles the receiving of emails SMTP – handles the sending of emails BitTorrent – provides peer-to-peer file sharing

Complete the following paragraph about a protocol suite, using words from the given list. Some words are not used. BitTorrent circuit switching layered link list peer‑to‑peer queue stack star TCP/IP The protocols in a ............................................................................. determine the interconnectivity rules for a ............................................................................. network model such as the ............................................................................. model. [3]

One mark for each correct word (Max 3) The protocols in a stack determine the interconnectivity rules for a layered network model such as the TCP/IP model

(b) Outline the purpose of the Link layer in the TCP/IP protocol suite. [2]

One mark per mark point (Max 2) MP1 To ensure correct network protocols are followed MP2 To enable the upper layers to access the physical medium // enables connection/ communication with the internet / network layer MP3 To be responsible for transporting data within the network/local segments MP4 To format the data into frames for transmission MP5 Maps IP addresses to MAC/Physical addresses

(a) State two examples of where it would be appropriate to use packet switching. [2]

One mark per mark point (Max 2) MP1 Packet switching is most commonly used on data networks such as the internet to send large data files that don’t need to be live streamed MP2 Packet switching is used when it is necessary to be able to overcome failed/faulty lines by rerouting. MP3 Packet switching is used when it is necessary for the communication to be more secure. MP4 Packet switching is used for high volume data transmission. MP5 Packet switching is used when it isn’t necessary to use all the bandwidth. MP6 Specific examples e.g. email, text messages, documents, VOIP etc. (up to two marks)

(b) Give four differences between circuit switching and packet switching. [4]

One mark per mark point (Max 4) MP1 Circuit switching uses a dedicated channel to make communication, whereas packet switching forms data into packets to transmit over a digital network. MP2 The dedicated path for circuit switching must be established before the transfer of data can commence, which is not the case with packet switching (as it doesn’t require a dedicated path). MP3 Data in packet switching is split into packets, in circuit switching the message remains intact. MP4 All of the transmission in circuit switching follows the same path whereas different packets in packet switching can take different routes. MP5 The message is received in the same order in which it is sent with circuit switching, but with packet switching, the packets can be received out of order (for assembly at the destination). MP6 Circuit switching is implemented at the physical layer while packet switching is implemented at the network layer. MP7 Circuit switching uses the whole bandwidth of the channel used, packet switching can share bandwidth. MP8 Circuit switching communication ends with an error but packet switching allows packets to be re-sent. MP9 Circuit switching is a simpler process than packet switching.

(a) Encryption is used to scramble data to make it meaningless if intercepted. Describe the purpose of quantum cryptography. [2]

One mark per mark point (Max 2) MP1 to produce a virtually unbreakable encryption system / send virtually un-hackable secure messages … MP2 …using the laws / principles of quantum mechanics / properties of photons MP3 detects eavesdropping … MP4 …because the properties of photons change MP5 to protect security of data transmitted over fibre optic cables MP6 to enable the use of longer keys

(b) Explain the differences between symmetric and asymmetric cryptography when encrypting and decrypting data. [3]

One mark per mark point (Max 3) MP1 Symmetric cryptography uses a single key to encrypt and decrypt messages, Asymmetric cryptography uses two. MP2 The symmetric key is shared, whereas with asymmetric, only the public key is shared (and the private key isn’t). MP3 … the risk of compromise is higher with symmetric encryption and asymmetric encryption is more secure. MP4 Symmetric cryptography is a simple process that can be carried out quickly, but asymmetric is much more complex, so slower. MP5 The length of the keys in symmetric encryption are (usually) shorter than those for asymmetric (128/256 bits v 2048 bits).

(a) Encryption is used to alter data into a form that makes it meaningless if intercepted. Describe the purpose of asymmetric key cryptography. [2]

One mark per mark point (Max 2) MP1 To provide better security MP2 … by using two different keys / a public key and a private key MP3 One of the keys is used to encrypt the message MP4 … the matching key is used to decrypt the message

(b) Identify two benefits and two drawbacks of quantum cryptography. [4] Benefit 1 ......................................................................................................................... Benefit 2 ......................................................................................................................... Drawback 1 ......................................................................................................................... Drawback 2 .........................................................................................................................

One mark per benefit (Max 2) MP1 Provides security based on laws of physics rather than mathematical algorithms, so more secure. MP2 To protect the security of data transmitted over fibre optic cables. MP3 Virtually unhackable. MP4 The performance of quantum cryptography is continuously improved, making it suitable for most valuable government/industrial secrets. MP5 Longer keys can be used MP6 Eavesdropping can be detected One mark per drawback (Max 2) MP1 Lacks many vital features such as digital signature, certified mail, etc. MP2 High cost of purchasing / maintaining equipment required. MP3 Currently only works over relatively short distances. MP4 Error rates are relatively high as technology is still being developed. MP5 Polarisation of light can change during transmission. MP6 Allows criminals and terrorists to hide their communications

(a) State, with a reason, where it would be appropriate to use circuit switching. [2]

One mark per mark point (Max 2)  Circuit switching is used where a dedicated path needs to be sustained throughout the call / communication // where the whole bandwidth is required // where a real time communication is used.  A typical application is standard voice communications / video streaming / private data networks

(b) Give two benefits and two drawbacks of circuit switching. [4] Benefit 1 ....................................................................................................... Benefit 2 ....................................................................................................... Drawback 1 ....................................................................................................... Drawback 2 .......................................................................................................

One mark per benefit (Max 2) MP1 Whole of bandwidth is available MP2 Dedicated communication channel increases the quality of transmission MP3 Data is transmitted with a fixed data rate MP4 No waiting time at switches MP5 Suitable for long continuous communication MP6 Fast method of data transfer MP7 Data arrives in the same order as it was sent MP8 Data can’t get lost MP9 Data all follows the same path / route MP10 Better for real-time MP11 Simple method of data transfer. One mark per drawback (Max 2) MP1 A dedicated connection makes it impossible to transmit other data even if the channel is free MP2 Not very flexible MP3 No alternative route in case of failure MP4 The time required to establish the physical link between the two stations can be too long MP5 The need to establish a dedicated path for each connection can have cost implications MP6 Dedicated channels require the whole bandwidth / bandwidth can’t be shared

(a) State two differences between symmetric and asymmetric encryption. [2]

One mark for each point • Symmetric encryption uses a single key and asymmetric encryption uses a pair of keys. • The symmetric single key is used by all, whereas only one of the keys for asymmetric encryption is available to everyone / one of the asymmetric encryption keys needs to be kept secret

(b) Explain the process by which an organisation may acquire its digital certificate. [4]

One mark for each point (Max 4) • The organisation requests a certificate from a Certificate Authority (CA) • The organisation may send their public key to CA • The organisation gathers all the information required by the CA in order to obtain their certificate, which includes information to prove their identity • The CA verifies the organisation’s identity • The CA generates / issues the certificate including the organisation’s public key (and other information

A message is encrypted using a private key and sent to an individual using asymmetric encryption. (a) State what is meant by a private key. [2]

One mark for each correct point (Max 2) • A private key is the unpublished/secret key/never transmitted anywhere. • It has a matching public key • It is used to decrypt data that was encrypted with its matching public key

(b) Describe the process of asymmetric encryption. [2]

One mark for each correct point (Max 2) • The message to be sent is encrypted using the recipient’s public key. // The message to be sent is encrypted using the sender’s private key. • The message is decrypted using the recipient’s private key. // The message is decrypted using the sender’s public key

(c) Explain how a digital signature is used to verify a message when it is received. [4]

One mark for each correct point (Max 4) • The message together with the digital signature is decrypted using the receiver’s private key • The digital signature received is decrypted with the sender’s public key to recover the message digest sent • The decrypted message received is hashed with the agreed hashing algorithm to reproduce the message digest of the message received • The two message digests are compared • … if both digests are the same the message has not been altered // if they are different the message has been altered

The TCP/IP protocol suite has four layers. The application layer provides user services. (a) Identify two protocols used by this layer. Describe the use of each protocol. [4] Protocol 1 ............................................................................................................................ Description ................................................................................................................................ Protocol 2 ................................................................................................................................. Description ................................................................................................................................

Protocol one mark, description one mark, max four Any two from  HTTP(S) (1) for sending and receiving web pages / hypertext documents (1)  FTP (1) for sending and receiving files over a network / between devices (1)  SMTP (1) for sending/uploading emails /push protocol (1)  POP(3) (1) for receiving/downloading emails /pull protocol (1)  IMAP (1) for receiving/downloading emails /pull protocol (1

(b) Identify two other layers of the TCP/IP protocol suite. Describe the function of each layer. [4] Layer 1 ....................................................................................................... Description ....................................................................................................... Layer 2 ....................................................................................................... Description .......................................................................................................

Layer one mark, matching function one mark, max four Any two from  Transport (1) handles packets (1)  Internet (1) handles transmission of data using IP addresses // provides (optimal) route (1)  Network Access (Interface) // (Data) Link // Physical (1) Handles how data is physically sent (1)

A digital signature is used to validate the authenticity of an electronic message. In order to produce a digital signature, a digital certificate is required. (a) State how a digital certificate is obtained. [3]

Any three from MP1 enquiry made to Certificate Authority (CA) MP2 enquirer’s details checked by CA MP3 if enquirer details verified by CA then public key is agreed MP4 CA creates/issues certificate that includes the enquirers public key MP5 encrypting data sent to/by CA with the CA’s public/private ke

(b) (i) Explain how a digital signature is produced before the message is sent. [3]

MP1 The message is hashed with (the agreed hashing algorithm)… MP2 … to produce a message digest MP3 The message digest is then encrypted with the sender’s private key to form the digital signature

(iii) Explain how the digital signature can be checked on receipt to ensure that the message has not been altered during transmission. [4]

Any four from MP1 The message together with the digital signature is decrypted using the receiver’s private key MP2 The digital signature received is decrypted with the sender’s public key to recover the message digest sent MP3 The decrypted message received is hashed with the agreed hashing algorithm to reproduce the message digest of the message received MP4 The two message digests are compared MP5 … if they are the same the message has not been altered // if they are different the message has been altered

A message is to be sent securely. Software uses a key to encrypt the message before it is sent. (a) (i) Give two reasons for using key cryptography. [2]

Any two from  To ensure the message is authentic // came from a trusted source  To ensure that only the intended receiver is able to understand the message  To ensure the message has not been altered during transmission  Non-repudiation, neither the sender or receiver can deny the transmission occurred

(b) When there is a secure exchange of key(s), the message is sent. The use of quantum cryptography is being considered for the secure exchange. (i) State two possible benefits of using quantum cryptography. [2]

Any two from  Any eavesdropping can be identified (as the state will be changed)  Integrity of the key once transferred can be guaranteed (cannot be copied and decrypted at a later date)  Longer/more secure keys can be exchanged

(ii) State two possible drawbacks of using quantum cryptography. [2]

Any two from  Limited range  requires dedicated fibre (optic) line and specialist hardware  cost of dedicated fibre (optic) line and specialist hardware is expensive  polarisation of light may be altered whilst travelling down fibre optic cables

9618 SECURITY

Flashcard

•

Information Technology (IT)

•

12th Grade

•

Practice Problem

•

Hard

Stephen Kimani

Used 1+ times

FREE Resource

Student preview

47 questions

Show all answers

FLASHCARD QUESTION

Front

(a) Describe circuit switching as a method of data transmission. [3]

Back

One mark per mark point (Max 3)

MP1 A dedicated circuit / channel is required

MP2 The circuit is established before the transmission begins

MP3 The circuit lasts for the whole of the transmission // The circuit is closed at the end of the transmission

MP4 Data travels in a continuous stream along the same route

MP5 Transmission is usually bidirectional

FLASHCARD QUESTION

Front

(b) State one benefit and one drawback of circuit switching as a method of data transmission. [2]

Benefit .....................................................................................................

Drawback

.....................................................................................................

Back

One mark for a benefit (Max 1)

MP1 No need for data to be reassembled // data / frames arrive in the same order in which they were sent

MP2 Suitable for real time transmission // fast data transfer rate

MP3 The whole of the bandwidth is available

One mark for a drawback (Max 1)

MP4 No other transmission can use the same circuit when it is in use // Bandwidth can be wasted as it cannot be used by other messages

MP5 Not secure // Can be intercepted as all data travelling along the same route

MP6 If there is a problem with the route the transmission ends // No other route is available without first doing the setup

MP7 The circuit is always there whether or not it’s being used

MP8 Can take time to set up before transmission starts

FLASHCARD QUESTION

Front

Describe how packet switching is used to transmit messages across a network. [3]

Back

One mark per mark point (Max 3)

MP1 The data to be transmitted is divided into equal sized packets

MP2 A packet header is attached to each packet containing key information

MP3 … such as source/destination IP addresses, packet number, etc

MP4 Packets are transmitted independently

MP5 … and may travel though different routes/paths to the destination

MP6 Routes are determined using a routing table//Packets take the optimum route depending on congestion

MP7 The packets usually arrive out of order

MP8 The packets are reassembled in the correct order at the destination // The packets are re-ordered using the sequence number/the header

MP9 If packets are missing/corrupted a re-transmission request is sent / packets are re-sent

FLASHCARD QUESTION

Front

State two benefits and two drawbacks of packet switching as a method of transmitting

messages across a network. [4]

Benefit 1 ...............................................................................................................................

Benefit 2 ...............................................................................................................................

Drawback 1 ...............................................................................................................................

Drawback 2

...............................................................................................................................

Back

One mark for each benefit (Max 2)

MP1 Packets are more likely to arrive because they can be re-routed if a problem occurs with one of the routes//Packets are more likely to arrive because if a packet is lost, it can be re-transmitted

MP2 Bandwidth can be shared allowing packets from different messages to share the same path

MP3 Considered secure as the packets generally travel via different routes

MP4 High data transmission rate is possible

One mark for each drawback (Max 2)

MP5 Time delay because packets need to be re-ordered/reassembled at the destination//Time delay caused by missing packets needing to be re-sent//Time delay because it has to share the bandwidth of the circuit / channel with other packets

MP6 Requires a complex algorithm to function

MP7 Needs lots of RAM to handle large amounts of data.

FLASHCARD QUESTION

Front

(a) Name and describe two protocols used by the Application Layer of the TCP/IP protocol suite. [4]

Protocol 1 .......................................................................................................

Description .......................................................................................................

Protocol 2 .......................................................................................................

Description

.......................................................................................................

Back

One mark for each correct name (Max 2)

One mark for each correct corresponding expansion (Max 2)

MP1 HTTP/HTTPS

MP2 For sending and receiving / transferring web pages / hypertext

MP3 FTP

MP4 For sending and receiving files over a network / between devices

MP5 POP3

MP6 Pull protocol / for receiving / downloading emails

MP7 IMAP

MP8 Pull protocol / for receiving / downloading emails

MP9 SMTP

MP10 Push protocol / for sending / uploading emails

MP11 BitTorrent

MP12 Peer-to-peer file sharing over a network

FLASHCARD QUESTION

Front

(b) Explain the purpose and function of the Application Layer in the TCP/IP protocol suite. [3]

Back

One mark per mark point (Max 3)

MP1 The application layer provides access to all the programs that exchange data // Interacts directly with user.

MP2 … used by, for example, web browsers, server software.

MP3 Communicates/enables data transfer to/from Transport layer // It allows applications to access the services used in other TCP/IP layers.

MP4 It defines the protocols that any application uses to allow the exchange of data

FLASHCARD QUESTION

Front

a) Describe circuit switching as a method of data transmission. [3]

Back

One mark per mark point (Max 3)

MP1 A dedicated circuit / channel is required

MP2 The circuit is established before the transmission begins

MP3 The circuit lasts for the whole of the transmission // The circuit is closed at the end of the transmission

MP4 Data travels in a continuous stream along the same route

MP5 Transmission is usually bidirectional

Access all questions and much more by creating a free account

Create resources

Host any resource

Get auto-graded reports

Continue with Google

Continue with Email

Continue with Microsoft

or continue with

Facebook

Apple

Others

Already have an account?

Similar Resources on Wayground

35 questions

02_ObliCon

Flashcard

•

12th Grade

50 questions

International Dances

Flashcard

•

12th Grade

50 questions

sfgjnfjdfgtlereviewerfndfjksdgns

Flashcard

•

44 questions

Project Management and HR Communication

Flashcard

•

Professional Development

38 questions

Math 3 EOC Formulas

Flashcard

•

11th Grade

41 questions

Differentiation and Integration Formulas

Flashcard

•

12th Grade

50 questions

Higher Admin Theory Marathon

Flashcard

•

11th Grade

37 questions

Properties of Dental Materials

Flashcard

•

University

Popular Resources on Wayground

24 questions

PBIS-HGMS Day 10

Quiz

•

6th - 8th Grade

10 questions

HCS SCI 03 Summer School Review 3

Quiz

•

3rd Grade

11 questions

Home Scope

Quiz

•

7th - 8th Grade

15 questions

HCS SCI 05 Summer School Assessment 3 Review

Quiz

•

5th Grade

35 questions

Lufkin Road Middle School Student Handbook & Policies Assessment

Quiz

•

7th Grade

18 questions

Geo 11.3 Area of Circles and Sectors

Quiz

•

9th - 11th Grade