Anna University Coimbatore 2009 B.E Electronics & Communication Engineering Computer network 2 ks - Question Paper

DEPARTMENT OF ELECTRONI CS & COMMUNI CATI ON ENGI NEERI NG
COMPUTER NETWORKS

PART A
UNIT – I
DATA COMMUNICATION
1. What is mean by data communication?
Data communication is the exchange of data (in the form of 1s and 0s) ranging from
two devices via a few form of transmission medium (such as a wire cable).
2. elaborate the 3 criteria necessary for an effective and efficient network?
The most important criteria are performance, reliability and security.
Performance of the network depends on number of users, kind of transmission
medium, the capabilities of the connected h/w and the efficiency of the s/w.
Reliability is measured by frequency of failure, the time it takes a link to recover
from the failure and the network's robustness in a catastrophe.
Security problems include protecting data from unauthorized access and viruses.
3. elaborate the 3 fundamental characteristics determine the effectiveness
of the data communication system?
The effectiveness of the data communication system depends on three
fundamental characteristics:
Delivery: The system must deliver data to the accurate destination.
Accuracy: The system must deliver data accurately.
Timeliness: The system must deliver data in a timely manner.
4. elaborate the advantages of distributed processing?
Advantages of distributed processing include security/encapsulation, distributed
databases, faster issue solving, security through redundancy and collaborative
processing.
5. Why are protocols needed?
In networks, communication occurs ranging from the entities in various systems. Two
entities cannot just send bit streams to every other and expect to be understood. For
communication, the entities must agree on a protocol. A protocol is a set of rules that
govern data communication.
6. Why are standards needed?
Co-ordination across the nodes of a network is necessary for an efficient
communication. If there are no standards, difficulties arise. A standard provides a
model or basis for development to which everyone has agreed.
7. For n devices in a network, what is the number of cable links needed for a
mesh and ring topology?
Mesh topology – n (n-1)/2
Ring topology – n
8. What is the difference ranging from a passive and an active hub?
An active hub contains a repeater that regenerates the received bit trends before
sending them out. A passive hub provides a simple physical connection ranging from the
attached devices.
9. Distinguish ranging from peer-to-peer relationship and a primary-secondary
relationship.
Peer-to-peer relationship: All the devices share the link equally.
Primary-secondary relationship: 1 device controls traffic and the others must
transmit through it.
10. presume six devices are organizes in a mesh topology. How many cables are

Earning:   Approval pending.