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(a)Explain each of the following terms;
(i)HTTP and HTML [2 marks ]
HTML is a mark-up language which describes
how pages are to be displayed (1).
HTTP is a simple application level protocol
where clients open TCP connections to request web pages (1).
(ii)Domain Name System [2 marks ]
Is a large distributed database application
(1) that provides a directory to translate domain names to IP address
(1).
(iii)Anonymous FTP [2 marks ]
Major program and data distribution mechanism
sites (1).FTP servers are
configured to allow outsiders to retrieve files from a restricted
area of the system without authorisation (1).
(b)Describe the three problems addressed by routers in wide-area
networks.[3 marks ]
Provides compatibility and connection between
networks using different protocols (1).
Finds suitable path from source to destination and move packets through
network (1).
Insulate the transport layer with details /topology of underlying
network (1).
(c)What are the advantages of having a transport layer between network
applications and the network layers?[3 marks ]
To bridge the gap between applications and
the network (1).Provide reliable data transfer from source to destination,independent
of the underlying networks and their topology (1).Changes to the network
do not affect applications on different hosts (1)
(d)Briefly describe the three major functions f the network layer.[3
marks ]
Concerned with getting packets from the source
to the destination,between
intermediate com uters called routers (1).Handles the roblems of incompatible
services,con .guration and architecture (1).Provides routing by finding
the path from source to destination across the networks (1).
(e)What are the three types of ICMP Messages?[3 marks ]
Error:indicates failure in routing or expired
TTL or bad port number (1).Control: functions like sending choke packet
or routing redirect (1).Network Management:testing functions like
echo request or echo reply (1).
(f)What are the advantages and disadvantages of having more layers
rather than fewer layers in a network architecture?[4 marks ]
Advantages:Handles complexity of networking,by
well defined functions at each layer (1) Results in many rotocol standards
for use (1)
Disadvantages:Increases erformance overhead,as each layer adds header
to actual data (1) Results in very complex interface between layers
(1)
(g)Distinguish between logical and physical address used in networks.[4
marks ]
Logical Address:Is a temporary one and changes
when the machine location changes. (1) Provided by Network Information
Centre to identify the machine uniquely across networks (1)
Physical Address:Is a permanent one and changes only when the NIC
card changes.(1) Provided by the manufacture of NIC card (1).
(h)The Internet user does not normally need to use IP addresses directly.
Explain how symbolic names are used instead.[4 marks ]
The Internet user refers to a host using
a domain name instead of an IP address (1). The name to address translation
data may be stored on each computer or on the DNS domain name server
(1) The user application will send domain name to server,and server
will send back the IP address (1).If the name server does not have
it in its local database,it can query the name server for the zone
above it (1).
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