Latest Computer Network Interview Questions 2011
1. What is mean by data communication?
Data communication is the exchange of data (in the form of 1s and 0s) between
two devices via some form of transmission medium (such as a wire cable).
2. What are the three 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, type 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 issues include protecting data from unauthorized access and viruses.
3. What are the three 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 correct destination.
Accuracy: The system must deliver data accurately.
Timeliness: The system must deliver data in a timely manner.
4. What are the advantages of distributed processing?
Advantages of distributed processing include security/encapsulation, distributed
databases, faster problem solving, security through redundancy and collaborative
processing.
5. Why are protocols needed?
In networks, communication occurs between the entities in different systems. Two
entities cannot just send bit streams to each 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 required for a
mesh and ring topology?
Mesh topology – n (n-1)/2
Ring topology – n
8. What is the difference between a passive and an active hub?
An active hub contains a repeater that regenerates the received bit patterns before
sending them out. A passive hub provides a simple physical connection between the
attached devices.
9. Distinguish between peer-to-peer relationship and a primary-secondary
relationship.
Peer-to-peer relationship: All the devices share the link equally.
Primary-secondary relationship: One device controls traffic and the others must
transmit through it.
10. Assume 6 devices are arranged in a mesh topology. How many cables are
needed? How many ports are needed for each device?
Number of cables=n (n-1)/2=6(6-1)/2=15
Number of ports per device=n-1=6-1=5
11. Group the OSI layers by function.
The seven layers of the OSI model belonging to three subgroups. Physical, data
link and network layers are the network support layers; they deal with the physical
aspects of moving data from one device to another. Session, presentation and
application layers are the user support layers; they allow interoperability among
unrelated software systems. The transport layer ensures end-to-end reliable data
transmission.
12. What are header and trailers and how do they get added and removed?
Each layer in the sending machine adds its own information to the message it
receives from the layer just above it and passes the whole package to the layer just
below it. This information is added in the form of headers or trailers. Headers are
added to the message at the layers 6,5,4,3, and 2. A trailer is added at layer2. At the
receiving machine, the headers or trailers attached to the data unit at the
corresponding sending layers are removed, and actions appropriate to that layer are
taken.
13. The transport layer creates a communication between the source and destination. What are the three events involved in a connection?
Creating a connection involves three steps: connection establishment, data
transfer and connection release.
14. What is the DC component?
Direct current is a zero-frequency signal with constant amplitude.
15. How does NRZ-L differ from NRZ-I?
In the NRZ-L sequence, positive and negative voltages have specific meanings:
positive for 0 and negative for 1. in the NRZ-I sequence, the voltages are
meaningless. Instead, the receiver looks for changes from one level to another as its
basis for recognition of 1s.
Latest Computer Network Interview Questions 2011
