OCR J277 Mark Scheme - Network Models

OCR	GCSE (9-1) Computer Science Mark Scheme J277/01: Unit 1.3 Network Models

Question	Answer	Marks	Guidance
1	Equal status: Peer-to-Peer Central backups: Client-Server Distributed security: Peer-to-Peer Central failure: Client-Server	4	AO1 (Knowledge) 1 mark per correct tick. If a candidate ticks both boxes for a single row, award 0 marks for that row.
2a	Peer-to-Peer / P2P	1	Reject: LAN (LAN is the type of network, P2P is the model. The question asks for the model).
2b	Benefit: It is cheaper to set up / easier to maintain. (1) Explanation: ...because he does not need to buy an expensive server / hire a network manager. (1)	2	Examiner Note: Answers must refer to Alex or the home context. "Cheaper" on its own is NE (Not Enough)—must imply why (no server hardware costs).
2c	Drawback: Files are not centrally backed up / Backups are difficult. (1) Explanation: ...so Alex has to backup each computer individually. (1)	2	Focus: Distributed management. Reject: "Slower" without qualification. P2P is not inherently slower unless many devices access one peer simultaneously.
3a	The main computer / Back office computer (1)	1	Allow: The computer storing prices.
3b	The checkout computer / Till (1)	1
3c	Sends a request (for the price) to the server. (1) Sends the barcode data / scanned item data. (1)	2	Key Concept: The client requests a service. Reject: "It scans the item" (this is the input device, not the network role).
3d	Processes the request / Searches the database for the price. (1) Returns the price/result to the client (checkout). (1)	2	Key Concept: The server provides the service/resource.
4	Reason 1: Centralised Backups The school can backup all student data from one location (1)... which ensures no student work is lost if a local computer fails (1). Reason 2: Centralised Security / Updates Software updates / Anti-virus can be deployed centrally (1)... which saves time as they don't have to update 500 computers individually (1). Reason 3: User Access Control / Roaming Profiles Students can log in to any computer in the school (1)... and access their files because they are stored on the server (1).	5	Max 5 Marks. Examiner Note: The key here is Scalability and Management. The 5th mark is awarded for a particularly detailed explanation or linking the benefit specifically to the volume of students. Reject: "It is faster" (Client-server can actually be slower if the server is congested).