What are firewalls? Explain and discuss three methods they employ to secure a network. [8]

So the first thing to do for this question is break down the question into what the marks will be given for. As this question is not testing written communication you do not need to worry about writing long paragraphs analysing and comparing each method, but rather meet the points the question is looking for.This means the question can be broken down to: 2 marks for stating and explaining what a firewall is. 2 marks for each method, so one mark for stating it then the other for explaining how it works.A model answer would be:'A firewall is a piece of software or hardware used to monitor, accept or block network traffic coming in and out of the network. For example, this could be between the internet and a local network.The three methods used are packet filtering, stateful inspection, and proxy servers.Packet filtering is applying a set of static, preset rules to incoming/outgoing packets on the network. Through this unwanted packets can be dropped discretely or rejected with an alert. It operates on the bottom 3 layers of the OSI model.Stateful inspection is used to check whether connections are new, ongoing, or ending on the network. It applies packet filtering on new connections otherwise it just lets packets be sent freely, allowing it to operate faster than packet filtering. Operates on the bottom 4 layers of the OSI model.Proxy servers are a separate physical device between the outside and local network. This allows packets to be checked before ever making contact with the network. Operates on all 7 layers of the OSI model, because of this it can block specific applications from communicating with the network.'Breaking down this answer, it should easily get you the 8 marks for the question. At the start a firewall was clearly explained and an example was included to further emphasise the point made. Then a new paragraph was started for each other new marking point to make it easier for the examiner to spot your answers and give you the marks. Each point was then over answered to ensure if one of the points you made did not award you the marks, the other one will.