Dec 1998 NI222: Networks and the Internet (Question 1)

(a)	Explain the difference between each of the following parts of terms:
	(i) LAN and WAN	[2]
	Local Area Network spans a limited geographical area and is owned by either an individual or a company (1 mark). Wide Area Network is an interconnection of multiple networks covering a wide geographical area (1 mark).
	(ii) Intranet and Extranet	[2]
	Intranets are collections of networks that are administered by a single entity or organisation (1 mark). Extranets are the services provided to users outside the organisation through its own network (1 mark).
	(iii) Transport layer and network layer	[2]
	The network layer provides host-to-host routing for packets, without guarantee of delivery (1 mark). The transport layer offers stable, managed connections, with retransmission / acknowledgement opportunities (1 mark).
	(iv) Bridge and Router	[2]
	A bridge is a device used to interconnect networks using similar protocols (1 mark). A router is a device used to interconnect networks using dissimilar protocols (1 mark).
	(v) SMTP and HTTP	[2]
	Simple Mail Transfer Protocol is the most widely used Email application on the Internet to send and receive Email (1 mark). Hyper Text Transmission Protocol is a simple application level protocol used to transfer HTML files over the Internet (1 mark). Allow credit for other appropriate explanations.
(b)	Explain each of the following acronyms:
	(i) IETF	[2]
	Internet Engineering Task Force (1 mark) is an open organisation that publishes all of its technologies widely in Internet Drafts and in Requests For Comments (RFCs) (1 mark).
	(ii) MIME	[2]
	Multipurpose Internet Email Extensions (1 mark) is a standard which supports various forms of non-conventional Email such as multimedia messages and includes text files, postscript, GIF, JPG, audio, video and other media objects (1 mark).
	(iii) UDP	[2]
	User Datagram Protocol (1 mark) is the other main transport protocol (besides TCP) offering services to the user’s network applications such as Network File System (1 mark).
	(iv) WWW	[2]
	World-Wide Web is a collection of applications and servers and high-level protocols which runs over the Internet (1 mark). It is mainly used for distributing hypertext and images (1 mark). N.B. Do not allow a mark for saying that WWW denotes ‘World Wide Web’: that is just too easy.
	(v) DNS	[2]
	Domain Name System (1 mark) is a large distributed database application that provides a directory to translate domain names to IP addresses that can be used by TCP and IP (1 mark). Allow credit for other appropriate explanations.