1. What is a server program? What is a client program? Does a server program request and receive services from a client program? [20 marks] 2. Briefly describe how circuit switching works (three good sentences are sufficient). [20 marks] 3. Describe what a protocol is in the context of computer networks. [20 marks] 4. Explain the purpose and operation of each of the following protocols: (a) Hypertext Transfer Protocol (HTTP) [10 marks] (b) Domain Name System (DNS) [10 marks] 5. One example of Internet security attack is denial of service (DoS) and its distributed version (DDoS). (a) Describe this type of attack. [10 marks] (b) Can DoS-type attacks be used to attack the DNS (Domain Name System)? What would be the damage if such an attack is suc- cessful? [10 marks]