Lecture 10: Transport Layer, Security and Internet Applications

Question 1

Is the Transport Layer dealing with getting entire message from:
a) Network to Network
b) Device to Device
c) Process to Process

Answer 1

c) Process

Question 2

Name two resposiblities of Transport Layer.

Answer 2

1) Segmentation and reassembly (packetisation).
2) Service point addressing (making sure message gets to correct port number of correct process).

Question 3

Which layer is resposible for:
a) Errors inside single network?
b) Errors inbetween networks?

Answer 3

a) Datalink.
b) Transport.

Question 4

What are three factors of error control that sequence numbers look after?

Answer 4

Sequence control, packet loss control and duplication control.

Question 5

What does UDP stand for and is it connectionless or connection-oriented?

Answer 5

User Datagram Protcol and connectionless. Used for streaming.

Question 6

What does TCP stand for and is it connectionless or connection-oriented?

Answer 6

Transmission vControl Protocol and connection-oriented.

Question 7

What are the two resposibilities of the Session layer?

Answer 7

1) Dialog control: determining whether half-duplex or full-duplex (one way or two way comms, respectively).
2) Synchronisation: defines sync checkpoints in case of error or disaster recovery.

Question 8

What are the three resposibilities of the Presentation layer?

Answer 8

1) Translation: translating between character sets.
2) Encryption: for security purposes.
3) Compression: reducing data size for efficiency purposes.

Question 9

Name some different genres of security.

Answer 9

Computer security, computer system security, network security, physical security, operational security, procedural security and comms security.

Question 10

What is a symmetric algorithm with regards to security?

Answer 10

The encryption key is the same as the decryption key.

Question 11

Name three characteristics for ensuring protected information.

Answer 11

Confidentiality (cryptography and steganography), integrity (hash functions), authenticity (digital signatures).

Question 12

Does public key system use asymmetric or symmetric algorithm?

Answer 12

Asymmetric.

Question 13

What is the application layer resposible for?

Answer 13

It is the interface between users and the network.

Question 14

Name some application layer protocols on the internet.

Answer 14

Email, WWW, remote access, file transfer, address translation, host configuration.

Question 15

Describe the client-server model.

Answer 15

There is a client application that can request information or resources from a server application. There can be many clients to a single server and client is usually only running when required whereas server is usually all the time.

Question 16

What are the two types of clients? Describe t hem.

Answer 16

Fat clients: perform most of processing for themselves.
Thin clients: perform little or no processing for themselves.

Question 17

What is the DNS format?

Answer 17

From right to left, 2 letter country code, then domain name, organistion’s name and computer’s name.

Question 18

What does a VPN do?

Answer 18

It treats the internet as if it were your own LAN. It protects it and sometimes requires encryption.

Question 19

Name some types of email applications.

Answer 19

Simple Mail Transfer Protcol (SMTP), Multipurpose Internet Mail Extension (MIME), Post Office Protocol (POP)

Question 20

What is remote access? Name two types.

Answer 20

Remote access allows a user to remotely log into and operate a computer from another one. SSH and TELNET.

Question 21

What are the two connections that File Transfer Protocol establishes?

Answer 21

Control connection and data transfer connection.

Question 21

What is the most common format for toring information pages on the WWW?”

Answer 21

Hypertext Markup Language (HTML)

Question 22

What protocol must a web browser use to make requests to a web server?

Answer 22

Hypertext Transfer Protocol (HTTP)