# A-level Computing 2009/AQA/Problem Solving, Programming, Operating Systems, Databases and Networking/Communication and Networking
## Communication Methods

* Specification: Communication Methods
* Define both serial and parallel transmission methods and describe where they are used
* Consider the effect of distance on the transmission of data.
* Baud, bit rate, bandwidth, latency
* Define these terms.
* Differentiate between baud and bit rate.
* Consider the relationship between bit rate and bandwidth.
* Asynchronous data transmission
* Define asynchronous data transmission.
* Start and stop bits
* Describe the purpose of start and stop bits in asynchronous data transmission.
* Odd and even parity
* Explain the use of parity checks.
* Handshaking
* Explain what is handshaking in the context of data transmission.
* Protocol
* Explain what is meant by a protocol in this context.
* Baseband and Broadband
* Define each mode of network operation and describe where each is appropriate.

## Networks

* Specification: Networks
* Networks
* Local Area Networks & Wide Area Networks
* Contrast wide area and local area networks
* Network adapter
* Topology (Bus & Star)
* Define the term topology.
* Differentiate between physical and logical network topologies
* Describe in general terms the operation of these networks.
* Compare the advantages and disadvantages of each.
* Candidates should be able to compare local area networking with standalone operation.
* Network Segment
* Define the term and explain why local-area networks based on a bus topology are segmented.
* Peer-to-peer networking & Server-based networking
* Explain these terms and describe situations where these might be used.
* Thin client computing & Web services
* Compare and contrast thin client computing (software as a service, AJAX, Web 2.0, etc) vs rich client computing (client-server, peer-to-peer), web services as examples of ‘systems architectures’.
* Wireless networking (Wi-Fi & Bluetooth)
* Radio-based LAN protocols for connecting mobile/portable devices.
* Inter-networking
* Explain the meaning of the term inter-networking.
* Routers particularly, Gateways
* Define these and consider where and why they are used.
* Consider how routing is achieved across the Internet and how local area networks are connected to the Internet via gateways.
* Consider how a subnet mask is used to identify the network identifier part of an IP address.
* Be familiar with the role of MAC addresses in routing packets/frames.
* Distinguish between routable and non-routable IP addresses.

## Server Side Scripting

* Specification: Server-side scripting
* Common Gateway Interface (CGI)
* Server-side scripting – the basis of dynamic web page content.
* Practical experience of writing simple server-side scripts.
* Accessing data from a DBMS using server-side scripts.

## Internet Security

* Specification: Internet Security
* Firewalls
* Packet filtering.
* Proxy Server.
* Encryption
* Private/Public key encryption.
* Digital Signatures and Digital Certificates
* How they are obtained and used.
* Virus detection
* Discuss worms, spam, phishing, pharming as well as viruses, also vulnerabilities that these exploit and how to address them through improved code quality, monitoring, protection.
* Computer Security Procedures
* Authentication
* Authorisation
* Accounting.