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The Transmission Control Protocol/Internet Protocol (TCP/IP)
Official AQA 7517 section 4.9.4.
0
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaA LevelComputer ScienceFundamentals of communication and networking
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TCP/IP1 objectives
- TCP/IP: Describe the role of the four layers of the TCP/IP stack (application, transport, network, link). Describe the role of sockets in the TCP/IP stack. Be familiar with the role of MAC (Media Access Control) addresses. Explain what the well-known ports and client ports are used for and the differences between them.
Standard application layer protocols1 objectives
- Standard application layer protocols: Be familiar with the following protocols: • FTP (File Transfer Protocol) • HTTP (Hypertext Transfer Protocol) • HTTPS (Hypertext Transfer Protocol Secure) • POP3 (Post Office Protocol (v3)) • SMTP (Simple Mail Transfer Protocol) • SSH (Secure Shell). Be familiar with FTP client software and an FTP server, with regard to transferring files using anonymous and non-anonymous access. Be familiar with how SSH is used for remote management. Know how an SSH client is used to make a TCP connection to a remote port for the purpose of sending commands to this port using application level protocols such as GET for HTTP, SMTP commands for sending email and POP3 for retrieving email. Be familiar with using SSH to log in securely to a remote computer and execute commands. Explain the role of an email server in retrieving and sending email. Explain the role of a web server in serving up web pages in text form. Understand the role of a web browser in retrieving web pages and web page resources and rendering these accordingly.
IP address structure1 objectives
- IP address structure: Know that an IP address is split into a network identifier part and a host identifier part.
Subnet masking1 objectives
- Subnet masking: Know that networks can be divided into subnets and know how a subnet mask is used to identify the network identifier part of the IP address.
IP standards1 objectives
- IP standards: Know that there are currently two standards of IP address, v4 and v6. Know why v6 was introduced. 86
Public and private IP addresses1 objectives
- Public and private IP addresses: Distinguish between routable and non-routable IP addresses.
Dynamic Host Configuration Protocol (DHCP)1 objectives
- Dynamic Host Configuration Protocol (DHCP): Understand the purpose and function of the DHCP system.
Network Address Translation (NAT)1 objectives
- Network Address Translation (NAT): Explain the basic concept of NAT and why it is used.
Port forwarding1 objectives
- Port forwarding: Explain the basic concept of port forwarding and why it is used.
Client server model1 objectives
- Client server model: Be familiar with the client server model. Client sends a request message to server, server responds to request by replying with a response message to client. Be familiar with the Websocket protocol and know why it is used and where it is used. The Websocket specification defines an API (Application Programming Interface) establishing a full-duplex 'socket' connection between a web browser and a server over TCP. This means that there is a persistent connection between client and server, allowing both parties to send data at any time. Be familiar with the principles of Web CRUD Applications and REST: • CRUD is an acronym for: • C – Create • R – Retrieve • U – Update • D – Delete. • REST enables CRUD to be mapped to database functions (SQL) as follows: • GET → SELECT • POST → INSERT • DELETE → DELETE • PUT → UPDATE. Students should understand the principles: • database connected to browser using REST – Representational State Transfer - which relies on HTTP request methods • REST allows JavaScript to talk to server through HTTP • REST API (Application Programming Interface) created and run on server, browser Javascript calls API • JSON (JavaScript Object Notation) or XML can be used to transmit data between a server and web application • Javascript referenced by HTML file, eg index.html, is run in browser. Compare JSON (Java script object notation) with XML. JSON compared with XML is: • easier for a human to read • more compact • easier to create • easier for computers to parse and therefore quicker to parse.
Thin- versus thick-client computing1 objectives
- Thin- versus thick-client computing: Compare and contrast thin-client computing with thick-client computing.
Key terms
SocketMAC addressApplication layer protocolRemote managementNetwork identifierHost identifierSubnetSubnet maskIPv4IPv6Routable IP addressNon-routable IP address
Exam tips
- Name the layer and its specific role: When describing a TCP/IP layer, state both the layer name and what it does, such as the transport layer using port numbers to identify processes.
- State the protocol and its purpose: When asked about a protocol, give both its full name and its role, such as HTTP for web page transfer or SMTP for sending email.
Common mistakes
- Confusing addresses and ports: Explain that an IP address supports identification and routing to a device, a MAC address supports local-network delivery, and a port number identifies a process or service on a device.
- Confusing SMTP and POP3: SMTP is used for sending email, whereas POP3 is used for retrieving email.
Practice preview
- Which statement best describes the role of the application layer in the TCP/IP stack?
- Which TCP/IP layer is primarily responsible for communication between applications on different devices, using port numbers to identify processes?
- What is the main purpose of a MAC address in TCP/IP networking?
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