Paper 1 Network topologies

Question 1

Give two advantages and two disadvantages of using a star network.

Answer 1

Advantages:

• it is very reliable – if one cable or device fails then all the others will continue to work
• it is high-performing as no data collisions can occur

Disadvantages:

• it is expensive to install as this type of network uses the most cable (network cable is expensive)
• extra hardware is required (hubs or switches) which adds to cost
• if a hub or switch fails, all the devices connected to it will have no network connection

Question 2

Identify the medium that is commonly physically used to connect to a local area network.

Answer 2

Computers can be connected through Ethernet cables which connect to the Ethernet port. Connecting hardware such as a router has Ethernet ports.

Question 3

There are two main ways that data is transmitted between computers on a network. What is meant by circuit switching?

Answer 3

Circuit switching is a type of network configuration in which a physical path is obtained and dedicated to a single connection between two endpoints in the network for the duration of a dedicated connection. For example voice phone service uses circuit switching.

Question 4

There are two main ways that data is transmitted between computers on a network. What is meant by packet switching?

Answer 4

A mode of data transmission in which a message is broken into a number of parts which are sent independently, over whatever route is optimum for each packet, and reassembled at the destination.

Question 5

What is meant by computer protocol?

Answer 5

A set of rules or procedures for transmitting data between electronic devices, such as computers.
In order for computers to exchange information, there must be a preexisting agreement as to how the information will be structured and how each side will send and receive it.

Question 6

Many networking protocols exist. TCP/IP is pair of protocols used on the Internet, split into four key layers. Name the 4 networking layers.

Answer 6

Application layer, Transport layer, Network layer, Data link layer

Question 7

Explain the function of the Network layer.

Answer 7

Adds the sender’s IP address and that of the recipient. The network then knows where to send the message, and where it came from.

Question 8

Explain the function of the Application layer.

Answer 8

Encodes/decodes the message in a form that is understood by the sender and the recipient.

Question 9

Explain the function of the Transport layer.

Answer 9

Breaks down the message into small chunks (packets). Each packet is given a packet number and the total number of packets. The recipient uses this information to assemble the packets together in the correct order. It also allows the recipient to see if there are any missing packets.

Question 10

Explain the function of the Data link layer.

Answer 10

Enables the transfer of packets between nodes on a network, and between one network and another.