Edexcel GCSE Computer Science (1CP2) Exam Questions

• A LAN (1)
• The only correct answer is A. The correct answer is LAN (Local Area Network).
• B is not correct because a PAN connects devices around one person over a short range
• C is not correct because a VPN is a secure private connection made over a public network, not a network covering one building
• D is not correct because a WAN connects networks over a large geographical area

• C To reassemble the packets in the correct order (1)
• The only correct answer is C. The correct answer is To reassemble the packets in the correct order.
• A is not correct because error checking uses the error checking data in the packet, not the packet number
• B is not correct because the destination IP address identifies the destination device, not the packet number
• D is not correct because routers use the destination IP address to choose the route, not the packet number; routers may briefly buffer packets but do not use the packet number to store them

• C It forwards data packets towards their destination (1)
• The only correct answer is C. The correct answer is forwards data packets towards their destination.
• A is not correct because a router does not add the destination IP address to each data packet, the sending device does
• B is not correct because a router does not check each data packet for errors, the receiving device does
• D is not correct because a router does not put data packets back into the correct order, the receiving device does

Award one mark for:

• A (time) delay between data/a signal being sent and being received (1)

Allow 'the time taken for data to travel from source to destination'

Allow 'the time taken for data to arrive at its destination after it is sent'

Allow 'time lag/time delay'

Do not accept the amount of data that can be transferred per second (this is bandwidth)

Do not accept the speed of the connection/how fast data travels (this is speed, not latency)

Award one mark for any of the following up to a maximum of two marks:

• A block/unit/chunk of data (1)
• A piece of a file/message (1)
• Sent/transmitted across a network/the internet (1)
• Contains a header with the destination/source IP address (as well as the data) (1)
• Can be routed/forwarded by routers using the destination IP address (1)

Allow 'unit' on its own for the first mark

Do not accept 'data' on its own

Do not accept a header/destination IP address on its own without identifying a unit/block of data

Do not accept 'a connection/cable between computers'

Do not accept MAC address for the addressing point

Award up to two marks for a linked description such as:

• Routers connect/join different networks together (1) so packets can pass from one network to another on the way to the destination (1)
• A router receives a packet (1) and forwards it to the next router on the route to the destination (1)
• Routers read the destination IP address in the packet header (1) to decide where to send the packet next (1)
• Routers use a routing table (1) to choose the best/least congested route for each packet (1)
• Packets are passed from router to router (1) until they reach the network of the destination device (1)

Allow 'uses a routing table' on its own for (1) only.

Do not award a mark for vague statements such as 'routers send/direct data' or 'routers connect devices to the internet' unless they are developed to say how the packet is forwarded.

Do not award the second mark for 'finds the fastest way' unless the route choice is linked to the packet, e.g. choosing the route for each packet.

Routers assigning IP addresses to devices (DHCP/IP allocation) is a different role from reading a destination IP address; do not credit it.

Do not award credit for descriptions of splitting data into packets or reassembling packets.

Award up to two marks for a linked description such as:

• A standard/set of rules for connecting (two or more) devices using cables (1) to transmit/send data over a network/LAN (1)
• Defines how data is sent as electrical/light signals (1) along copper/fibre optic cable (1)
• Gives a device a wired connection to a switch/network (1) so it can send and receive data (1)
• Allows devices without Wi-Fi to join a network (1) by connecting them with a cable (1)

Allow cable/wired for the first mark.

Do not accept responses about wireless/radio connections; these relate to Wi-Fi.

Do not accept 'Ethernet is a cable/a type of cable' with no reference to rules or connecting devices to send data.

Do not accept responses describing TCP/IP or IP addressing; these are different protocols.

Do not award credit for naming Ethernet only.

Award up to two marks for a linked description such as:

• Each device/node is connected to more than one other device (1) so there is another route for the data to take (1)
• Data can be sent along a different path (1) to bypass the failed connection (1)
• There is no central device/switch to fail (1) so data can still be passed between the remaining devices (1)

Allow 'sensor' or 'node' for device.

Do not accept 'the failed connection repairs itself' or 'the data is stored until the connection works again'.

Do not accept responses that say a central switch sends the data by another route, as a mesh has no central device.

Do not award generic statements such as 'a mesh is reliable/resilient' without a description of how the data still reaches its destination.

Do not award descriptions of a bus or star network failing.

Accept a reference to a device failing only where the candidate also states that other connections/routes remain available.

Award up to two marks for a linked explanation such as:

• A LAN covers a small geographical area (1) because all the charity's computers are in one building/on one site (1)
• The charity can use its own cabling/equipment (1) so it does not need to rent leased lines from a telecoms provider (1)
• The charity owns the infrastructure (1) so it avoids the cost of leased lines/external connections that a WAN needs (1)
• The devices are close together (1) so the LAN can use short, high-speed cabling (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'it is faster/better/cheaper' on its own without a linked reason (e.g. short distance, own cabling, no leased lines).

Allow 'the LAN is private/secure' only with a linked reason such as the charity controls its own equipment.

Do not accept 'a LAN is local' or 'a WAN is too far/expensive' without a linked reason about the small area or leased lines.

Do not accept 'the computers are in one building/on one site' on its own because it repeats the stem; it must be linked to a reason such as a LAN covering a small geographical area.

Do not accept 'stronger Wi-Fi/signal' as a reason.

Do not accept 'can share files/printers' on its own because this is a reason for any network, not for choosing a LAN over a WAN.

Award up to two marks for a linked explanation such as:

• If a packet is damaged/lost only that packet has to be resent (1) so the rest of the video does not need to be sent again (1)
• The video can still be delivered if one router/route fails (1) because routers can send the packets by an alternative route (1)
• Packets from the video can share the network with other users' data (1) because routers send packets from many users along the same connections (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'it is faster/quicker' on its own without saying why it is faster, e.g. because packets can take a less busy route.

Do not accept 'it is more secure/safer' on its own without expansion as to why it is more secure.

Do not accept 'the video is made smaller/compressed' - splitting a file into packets does not reduce the total amount of data.