Edexcel GCSE Computer Science (1CP2) Exam Questions

• C 32 (1)
• The only correct answer is C. The correct answer is 32.
• A is not correct because 4 is the number of groups of numbers in an IPv4 address
• B is not correct because 8 is the number of bits in each group of an IPv4 address
• D is not correct because 128 is the number of bits in an IPv6 address

• 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 SMTP (1)
• The only correct answer is C. The correct answer is SMTP.
• A is not correct because FTP is used to upload and download files
• B is not correct because HTTP is used to request web pages
• D is not correct because TCP is a transport-layer protocol that splits data into packets and reassembles them

• B 192.168.0.1 (1)
• The only correct answer is B. The correct answer is 192.168.0.1.
• A is not correct because it has only three groups of numbers; an IPv4 address has four groups separated by dots
• C is not correct because it has five groups of numbers; an IPv4 address has four groups separated by dots
• D is not correct because 256 is outside the valid range for a group, which is 0 to 255

• A It is not affected by interference from other wireless devices (1)
• The only correct answer is A. The correct answer is that a wired connection is not affected by interference from other wireless devices.
• B is not correct because a wired connection does not let staff move around the office; being able to move around is a benefit of a wireless connection
• C is not correct because a new device needs a cable and a free port to join a wired network, which takes longer than joining a wireless network
• D is not correct because a wired connection does need a cable; it is a wireless connection that does not need one

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

• It connects many separate networks/LANs together (1) that are located all over the world (1)
• It covers a large geographical area/is worldwide (1) so networks/devices in different countries can be connected together (1)
• It uses infrastructure/leased lines provided by many different companies (1) so no single organisation owns/controls it (1)

Allow a statement that the internet is worldwide/covers a large geographical area (1), but the second mark needs the link to networks/devices being connected across that distance (1).

Do not accept a bare 'it is very big/large' with no reference to the area covered, the distance or networks.

Do not accept answers that describe a LAN instead of the internet/WAN, such as 'it covers one building'.

Do not accept descriptions of what the internet is used for, such as sending emails or viewing websites.

Do not accept descriptions of the internet's hardware/structure (cables, routers, servers) unless they refer to the wide area covered.

Do not accept responses that say the internet is wireless or has no cables.

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

• 300 million bits (1) are transferred/downloaded every second (1)
• 300 megabits of data (1) are received each second (1)
• Each second (1) 300,000,000 bits arrive at the device (1)
• The connection can receive (1) 300 megabits of data in one second (1)

Allow '300 million bits per second' (2) as it states both the quantity and the time.

Accept 'megabits', 'Mb' or 'Mbps' as the unit of bits.

Do not accept 'megabytes'/'MB' or answers that give no unit of bits, e.g. '300 units of data per second'.

Do not award marks for simply repeating the question, e.g. '300 megabits per second' or 'it has a speed of 300 Mbps', with no statement of the data transferred/received and the time.

Do not accept answers that only say the connection is fast.

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

• All devices share a single cable/backbone (1) so if two devices transmit at the same time their signals collide (1)
• Signals travel in both directions along the cable (1) so data from different devices can meet/interfere with each other (1)
• Only one device can transmit at a time (1) so devices must wait until the cable is free before sending (1)
• The more devices that are added to the network (1) the more often collisions happen/the slower the network becomes (1)

Allow 'the data is corrupted and has to be resent' as the linked development of a collision.

Do not accept responses about a broken/missing cable or faulty terminators, as the whole network failing is a different issue.

Do not award 'the data is lost forever' as a result of a collision.

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

• Other electrical/radio devices nearby (1) interfere with the wireless signal so data is corrupted (1)
• Interference corrupts data (1) so the data has to be resent, which increases latency/slows the transfer (1)
• Interference reduces the strength of the signal received (1) which lowers the data transfer rate the connection can support (1)
• Interference makes the connection drop (1) so data transfer stops/devices have to reconnect (1)

Do not accept responses that only name a device (microwave, phone) without saying how it affects the network.

Do not accept responses that only state the network becomes slower without saying what causes the interference or how it affects the data.

Do not accept responses about wired connections or cables.

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

• The receiver can put the packets back into the correct order (1) because packets may arrive out of order/take different routes (1)
• The receiver can see if a packet is missing (1) because the sequence of numbers shows a gap (1)
• The receiver knows when the whole file has arrived (1) because the total number of packets/last packet number is known (1)

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

Allow 'so the packets can be put back in the correct order/reassembled' for the first mark, but the second mark needs the reason, i.e. packets may arrive out of order/take different routes.

Do not accept 'so the packets can be identified' without stating what the number is used for, e.g. reordering or spotting a missing packet.

Do not accept 'so the router knows where to send it' - the router uses the destination IP address, not the packet number.