Training for mathematics Olympiad classes

Training for mathematics Olympiad classes and Kishore Vaigyanik Protsahan Yojna Scholarship (KVPY) classes, organised by the Nehru Children’s Cultural Association, Adyar, will commence on September 1 and continue till December 30. The classes will be held on all Saturdays (from 4 p.m. to 6 p.m.) and on Sundays (from 9 a.m. to 12 noon) at P.S. Higher Secondary School, 215, Ramakrishna Math Road, Mylapore.

For registration, contact M.R. Sugumaran, president, Nehru Children’s Cultural Association, Ph: 81444 16484 / 2445 3014.

Improving your Time Management

Time management is the ultimate art which once mastered can prove to do wonders for any human being. For busy workers and managers, effective time management can be very fruitful and healthy. Of course the art is not easy to master and is even more difficult to maintain. The key is to manage and divide your time effectively allowing yourself time to breath and rest. A busy schedule with no time to rest is bound to lead you to fall behind. We are not always energetic and the body as well as the brain needs breaks to perform at its maximum potential. Effective time management is a primary means to a less stressful life and is most profitable. Here are some tips and means to effective management.

Create A Plan

Always have a scheduled plan for your daily routine. Get up early in the morning and sleep on time in the night. Rest is a must part of the schedule and you cannot cheap out on it. The daily body requirement for sleep is 6-8 hours a day and hence, on your 24 hours day plan, this time is booked for rest. You can take it in breaks like 6 hours in the night and 2 hours of sleep in the evening. Also allow time for nutritious diet. Three meals a day is mandatory for healthy living.

Create Information Centers

Where is your plan written or scheduled? What determines your daily activities? Usually we gather our daily assignments from work, then from home and then what ever we want to do for ourselves. These assignments are collected from information centers like an e-mail, your mom leaving a post stamp on the fridge or your phone messages. Hence, the lesser the information centers, the more easy it is for you to look for assignments or chores to do. If you have multiple e-mail ids, forward them to all to one so you know where to look, write down all the things to do (from post stamps, phone texts, messages, family, etc.) in one source, maybe a notepad or the to-do-list app on your phone (task manager).

Prioritize Your Tasks

Figure out what tasks must be done first and what must be done later. Leave the important once to be done first and the less significant tasks for a later time.

Strike Down Work When Complete

Once you’ve completed the task, strike it off your work list so you don’t get confused. Keep yourself updated, as in make sure your e-mail and list is updating because sometimes some work might need to be delayed and that saves you time for other important work to be done.

Target To Be Early

If you can, then keep your watch clock five-ten minutes ahead. This way you’ll always be 5-10 minutes ahead of schedule and your work will always be on time.

Focus

All work can be completed easily, early and effectively if you keep focusing on the job. Worrying if you’re on time can be distracting and reduces the quality of your work despite you being early, so focus on quality rather than on time otherwise you’ll mess up your entire schedule.

Delegate

If you’re a manager you probably have many subordinates working for you. Even if you’re not you have colleagues and family. Delegate to them as much work as you can if you know they can handle it. This takes a lot of burden off your shoulders and you can concentrate on your work.

Eliminate Your Time Wasters

Avoid distractions or anything that wastes your time. Standing at the electronics store watching TV is a waste and so is arguing on facts you are not completely aware of. Most time is wasted travelling. Center your location so you are equally distant to all your work.

Evaluate How You’re Spending Your Time

At the end of the day evaluate your schedule and see what improvements you can make on them for tomorrow. See where you can peg time for tasks and where you need breaks if you get tired and restless.
Time management is really an art and any well planned individual tends to gain more than any unplanned individual.

Conference - September 13, 2012 - Enhancing Subscriber Retention With Policy Control Servers

	With the advent of 3G and 4G technologies, the Indian operators have truly started focusing on data for revenue generation. However this is not without challenges. Operators face the challenge of differentiating their broadband offerings; network congestion and subscriber retention. Policy control takes a center stage in this scenario. The question being faced by the Indian telcos is not whether to implement policy control but how to take the maximum advantage of it. A converged policy control solution will go a long way in reducing complexity, in aiding faster decision making, and enhancing subscriber retention as also in creating opportunities for cross bundling of services. The roundtable will debate on the following key topics: Growing importance of Policy in subscriber retention and revenue generation It will also touch up on the significance of converged policy solutions to realize the full potential of broadband services Agenda 6:00 - 6:30 p.m.        Registration 6:30 - 6:40 p.m.       Welcome Remarks Ms. Gagandeep Kaur, Executive Editor, Light Reading India 6:40 p.m. - 7:00 p.m. Converge and Optimize 2G, 3G, 4G, LTE infrastructure investment to improve operational efficiency: Optimize distribution of (big growth of data) traffic over the network Improving subscriber management and services Monetizing subscriber-based information for new revenue channels Mohamed Tanana, Global Telecom Solution Architect, F5 Networks 7:00 - 8:00 p.m. Roundtable Discussion: Enhancing Subscriber Retention with Policy Control Server 8:00 - 9:30 p.m. Closing Remarks & Networking Dinner Reception Click Here to Register About F5 Networks F5 Networks, Inc., the global leader in Application Delivery Networking (ADN), helps the world's largest enterprises and service providers realize the full value of virtualization, cloud computing, and on-demand IT. F5® solutions help integrate disparate technologies to provide greater control of the infrastructure, improve application delivery and data management, and give users seamless, secure, and accelerated access to applications from their corporate desktops and smart devices. An open architectural framework enables F5 customers to apply business policies at "strategic points of control" across the IT infrastructure and into the public cloud. F5 products give customers the agility they need to align IT with changing business conditions, deploy scalable solutions on demand, and manage mobile access to data and services. Enterprises, service and cloud providers, and leading online companies worldwide rely on F5 to optimize their IT investments and drive business forward. F5 offers carrier-grade solutions that are used by all of the top 10 mobile and fixed service providers worldwide, and by every major cable company in the U.S. and Europe. F5 provides a unified foundation with deep session intelligence, integrated services management, and dynamic adaptability to fit any service offering. You gain the ability to scale to meet growing demand, control infrastructure costs, reduce operating complexity, and quickly provision profitable, differentiated services. For more information, go to www.f5.com.

Aditya Birla group to set up vocational training center in Mavoor

The Aditya Birla group plans to set up a vocational training centre in Mavoor, Kerala, where the group’s manufacturing units once were.

In 1968, Grasim (an Aditya Birla company) set up viscose staple fibre and rayon grade pulp units across 320 acres in Mavoor.

In the backdrop of alleged environmental concerns, the company closed down the units in 1999 citing lack of raw material.

The 320 acres of land, which the Aditya Birla group owns, will now be used for a vocational training center. The Aditya Birla Centre for Community Initiatives and Rural Development, the group’s CSR (corporate social responsibility) arm, plans to invest Rs 100 crore in this project.

The training facility expects to train 10,000 people a year across vocations such as Ayurveda, tailoring, carpentry, masonry and plumbing, said Rajashree Birla, wife of the late Aditya Birla, who is spearheading the corporate social responsibility (CSR) initiatives of the group.

The Aditya Birla Centre for Community Initiatives and Rural Development already runs 22 vocational training units across the country.

The Center plans to pump in Rs 150 crore this year into other CSR initiatives.

They include a cancer centre at the Aditya Birla Memorial Hospital in Pune and a telemedicine set-up at the G. D. Birla Hospital in Ujjain.

FICCI TIE-UP

The Aditya Birla group has tied up with the Federation of Indian Chambers of Commerce and Industry (FICCI) to mentor companies, especially small and medium enterprises, on CSR activities. The group hopes this initiative will gather steam this year, said Rajashree Birla, on the sidelines of a seminar organised by FICCI on CSR.

Speaking at the seminar, she said that organisations must embed CSR in their mainstream activities.

“CSR must be integrated into the marketing and community initiatives. Companies must also encourage employ volunteerism.

“CSR stimulates business development. Customers prefer companies with a social conscience.

“Shareholders and investors also gravitate towards organisations with social responsibility,” she elaborated.

Go - New Language from Google

Courtesy - Drdobbs

Go is a fundamental rethinking of native languages that improves greatly on C while maintaining that language's minimalism.

Earlier this year, we ran an article about the emerging crop of native languages. The group included D, Go, Rust, and Vala. I promised then that we would eventually explore these languages in greater detail. This week starts that fun journey with what will be a five-part series on Go, the new language from Google. Unlike past tutorial series in Dr. Dobb's, we will run the articles in consecutive weeks, so that you can be up and running quickly.

More than the other languages on the list, Go really attracts me. While I am by no means an expert in it, I like what I've seen so far. My enjoyment derives, as you'll see, from an appreciation of the maturity of feature selection, rather than from a gee-whiz enthusiasm that new languages can generate on first exposure. (I confess I am susceptible to this kind of excitement as well—which is why I can recognize the difference with Go.) These features in particular appeal to me:

Fast and simple compilation. Go compiles fast. In fact, it compiles so fast, it can easily be used as a scripting language. Several reasons for the compilation speed are that it does not use header files; if a module depends on A, which in turn depends on B, a change in A requires only recompiling the original module and the A dependency; finally, the object modules contain enough dependency information that the compiler needs no make file. You simply compile the main module and it will automatically compile everything in the project that needs to be updated. Cool, eh?

Error handling through multiple return values. There are two primary paradigms today in native languages for handling errors: return codes, as in C, or exceptions, as in OO alternatives. Neither system is ideal. But of the two, return codes is the more frustrating, because returning error codes often conflicts with returning other data from the function. Go solves this by allowing functions to return multiple values. One value that returned for functions that you designate is of type error and can be checked anytime a function returns. If you don't care about the error value, you don't check it. In either case, the regular return values of the function are available to you.

Simplified composition (in preference to inheritance). Types can be qualified as members of a group of objects by the use of interfaces, which, like they do in Java, specify behavior. So, for example, the io package in the standard library defines a Writer that specifies one method, a Write function with array of chars as the the input parameter and return values of integer and error type). Any type that implements a Write method with the same signature is a de facto implementation of the io.Writer interface. This design decouples code rather elegantly. It also simplifies mocking objects for unit testing. For example, if you want to test one method in a Database object, in standard languages you have to create a database object that requires lots of initialization and protocol in order to create the mock. In Go, if the method under test implements an interface, you can create any object with that interface and you're good to go. So, you could create MockDatabase, which is a minimal object that implements only the few methods necessary to run the interface that needs to be mocked—no constructor, no added features, just the methods.

Simplified concurrency. Concurrency in Go is made comparatively easy. Put the keyword 'go' in front of any function and that function will run in its own go-routine (a very light thread). Go-routines communicate through channels that are essentially blocking message queues. The usual tools for mutual exclusion are available, but Go makes it simple just to kick off concurrent tasks and coordinate via channels.

Excellent error messages. No language I've seen comes close to Go in the quality of the diagnostics it emits. For example, if a program deadlocks, the Go runtime notifies you of this and, to the extent it can, tells you which threads are causing the deadlock! Compiler error messages are similarly detailed and useful.

Grab bag: There are other appealing features, which I'll quickly run through here: higher-order functions, garbage collection, hash maps and expandable arrays built into the language (so part of the language syntax, not brought in as a library), and so on.

Of course, not everything is rainbows and lollipops. The tools are still fairly immature and the community is small, but with Google behind the language, both aspects are sure to be remediated. While many languages—notably D, Rust, and Vala—aim to simplify C++ and add specific features, they all feel to me like “C++ with better features.” In Go, however, there's been a fundamental rethinking of how native languages should operate. And from that perspective comes an elegance of implementation that does away with many problems. Even if you have no particular need to consider Go, I think that by kicking the tires on the language, you'll find yourself appreciating many of its features. Cheers!

Network Technical Interview Question Bank - Part 1 More than 100+ Questions

1. Define Network?

A network is a set of devices connected by physical media links. A network is recursively is a connection of two or more nodes by a physical link or two or more networks connected by one or more nodes.

2. What is a Link?

At the lowest level, a network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Link.

3. What is a node?

A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or optical fiber. Such a physical medium is called as Links and the computer it connects is called as Nodes.

4. What is a gateway or Router?

A node that is connected to two or more networks is commonly called as router or Gateway. It generally forwards message from one network to another.

5. What is point-point link?

If the physical links are limited to a pair of nodes it is said to be point-point link.

6. What is Multiple Access?

If the physical links are shared by more than two nodes, it is said to be Multiple Access.

7. What are the advantages of Distributed Processing?

a. Security/Encapsulation
b. Distributed database
c. Faster Problem solving
d. Security through redundancy
e. Collaborative Processing

8. What are the criteria necessary for an effective and efficient network?

a. Performance
   It can be measured in many ways, including transmit time and response time. b. Reliability
   It is measured by frequency of failure, the time it takes a link to recover from a failure, and the network's robustness.
c. Security
   Security issues includes protecting data from unauthorized access and virues.

9. Name the factors that affect the performance of the network?

a. Number of Users
b. Type of transmission medium
c. Hardware
d. Software

10. Name the factors that affect the reliability of the network?

a. Frequency of failure
b. Recovery time of a network after a failure

11. Name the factors that affect the security of the network?

a. Unauthorized Access
b. Viruses

12. What is Protocol?

A protocol is a set of rules that govern all aspects of information communication.

13. What are the key elements of protocols?

The key elements of protocols are
a. Syntax
   It refers to the structure or format of the data, that is the order in which they are presented.
b. Semantics
   It refers to the meaning of each section of bits.
c. Timing
   Timing refers to two characteristics: When data should be sent and how fast they can be sent.

14. What are the key design issues of a computer Network?

a. Connectivity
b. Cost-effective Resource Sharing
c. Support for common Services
d. Performance

15. Define Bandwidth and Latency?

Network performance is measured in Bandwidth (throughput) and Latency (Delay). Bandwidth of a network is given by the number of bits that can be transmitted over the network in a certain period of time. Latency corresponds to how long it t5akes a message to travel from one end off a network to the other. It is strictly measured in terms of time.

16. Define Routing?

The process of determining systematically hoe to forward messages toward the destination nodes based on its address is called routing.

17. What is a peer-peer process?

The processes on each machine that communicate at a given layer are called peer-peer process.

18. When a switch is said to be congested?

It is possible that a switch receives packets faster than the shared link can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to congested state.

19. What is semantic gap?

Defining a useful channel involves both understanding the applications requirements and recognizing the limitations of the underlying technology. The gap between what applications expects and what the underlying technology can provide is called semantic gap.

20. What is Round Trip Time?

The duration of time it takes to send a message from one end of a network to the other and back, is called RTT.

21. Define the terms Unicasting, Multiccasting and Broadcasting?

If the message is sent from a source to a single destination node, it is called Unicasting.
If the message is sent to some subset of other nodes, it is called Multicasting.
If the message is sent to all the m nodes in the network it is called Broadcasting.

22. What is Multiplexing?

Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link.

23. Name the categories of Multiplexing?

a. Frequency Division Multiplexing (FDM)
b. Time Division Multiplexing (TDM)
   i. Synchronous TDM
   ii. ASynchronous TDM Or Statistical TDM.
c. Wave Division Multiplexing (WDM)

24. What is FDM?

FDM is an analog technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals to be transmitted.

25. What is WDM?

WDM is conceptually the same as FDM, except that the multiplexing and demultiplexing involve light signals transmitted through fiber optics channel.

26. What is TDM?

TDM is a digital process that can be applied when the data rate capacity of the transmission medium is greater than the data rate required by the sending and receiving devices.

27. What is Synchronous TDM?

In STDM, the multiplexer allocates exactly the same time slot to each device at all times, whether or not a device has anything to transmit.

28. List the layers of OSI

a. Physical Layer
b. Data Link Layer
c. Network Layer
d. Transport Layer
e. Session Layer
f. Presentation Layer
g. Application Layer

29. Which layers are network support layers?

a. Physical Layer
b. Data link Layer and 
c. Network Layers

30. Which layers are user support layers?

a. Session Layer

b. Presentation Layer and 
c. Application Layer

31. Which layer links the network support layers and user support layers?

The Transport layer links the network support layers and user support layers.

32. What are the concerns of the Physical Layer?

Physical layer coordinates the functions required to transmit a bit stream over a physical medium.
a. Physical characteristics of interfaces and media
b. Representation of bits
c. Data rate
d. Synchronization of bits
e. Line configuration
f. Physical topology
g. Transmission mode

33. What are the responsibilities of Data Link Layer?

The Data Link Layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node-node delivery.
a. Framing
b. Physical Addressing
c. Flow Control
d. Error Control
e. Access Control

34. What are the responsibilities of Network Layer?

The Network Layer is responsible for the source-to-destination delivery of packet possibly across multiple networks (links).
a. Logical Addressing
b. Routing

35. What are the responsibilities of Transport Layer?

The Transport Layer is responsible for source-to-destination delivery of the entire message.
a. Service-point Addressing
b. Segmentation and reassembly
c. Connection Control
d. Flow Control
e. Error Control

36. What are the responsibilities of Session Layer?

The Session layer is the network dialog Controller. It establishes, maintains and synchronizes the interaction between the communicating systems.
a. Dialog control
b. Synchronization

37. What are the responsibilities of Presentation Layer?

The Presentation layer is concerned with the syntax and semantics of the information exchanged between two systems.
a. Translation
b. Encryption
c. Compression

38. What are the responsibilities of Application Layer?

The Application Layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as e-mail, shared database management and other types of distributed information services.
a. Network virtual Terminal
b. File transfer, access and Management (FTAM)
c. Mail services
d. Directory Services

39. What are the two classes of hardware building blocks?

Nodes and Links.

40. What are the different link types used to build a computer network?

a. Cables
b. Leased Lines
c. Last-Mile Links
d. Wireless Links

41. What are the categories of Transmission media?

a. Guided Media
  i. Twisted - Pair cable
    1. Shielded TP
    2. Unshielded TP
  ii. Coaxial Cable
  iii. Fiber-optic cable
b. Unguided Media
  i. Terrestrial microwave
  ii. Satellite Communication

42. What are the types of errors?

a. Single-Bit error
  In a single-bit error, only one bit in the data unit has changed
b. Burst Error
  A Burst error means that two or more bits in the data have changed.

43. What is Error Detection? What are its methods?

Data can be corrupted during transmission. For reliable communication errors must be deducted and Corrected. Error Detection uses the concept of redundancy, which means adding extra bits for detecting errors at the destination. The common Error Detection methods are 
  a. Vertical Redundancy Check (VRC)
  b. Longitudinal Redundancy Check (VRC)
  c. Cyclic Redundancy Check (VRC)
  d. Checksum

44. What is Redundancy?

The concept of including extra information in the transmission solely for the purpose of comparison. This technique is called redundancy.

45. What is VRC?

It is the most common and least expensive mechanism for Error Detection. In VRC, a parity bit is added to every data unit so that the total number of 1s becomes even for even parity. It can detect all single-bit errors. It can detect burst errors only if the total number of errors in each data unit is odd.

46. What is LRC?

In LRC, a block of bits is divided into rows and a redundant row of bits is added to the whole block. It can detect burst errors. If two bits in one data unit are damaged and bits in exactly the same positions in another data unit are also damaged, the LRC checker will not detect an error. In LRC a redundant data unit follows n data units.

47. What is CRC?

CRC, is the most powerful of the redundancy checking techniques, is based on binary division.

48. What is Checksum?

Checksum is used by the higher layer protocols (TCP/IP) for error detection

49. List the steps involved in creating the checksum.

a. Divide the data into sections
b. Add the sections together using 1's complement arithmetic
c. Take the complement of the final sum, this is the checksum.

50. What are the Data link protocols?

Data link protocols are sets of specifications used to implement the data link layer. The categories of Data Link protocols are 1. Asynchronous Protocols
2. Synchronous Protocols
  a. Character Oriented Protocols
  b. Bit Oriented protocols

51. Compare Error Detection and Error Correction:

The correction of errors is more difficult than the detection. In error detection, checks only any error has occurred. In error correction, the exact number of bits that are corrupted and location in the message are known. The number of the errors and the size of the message are important factors.

52. What is Forward Error Correction?

Forward error correction is the process in which the receiver tries to guess the message by using redundant bits.

53. Define Retransmission?

Retransmission is a technique in which the receiver detects the occurrence of an error and asks the sender to resend the message. Resending is repeated until a message arrives that the receiver believes is error-freed.

54. What are Data Words?

In block coding, we divide our message into blocks, each of k bits, called datawords. The block coding process is one-to-one. The same dataword is always encoded as the same codeword.

55. What are Code Words?

"r" redundant bits are added to each block to make the length n = k + r. The resulting n-bit blocks are called codewords. 2ⁿ - 2^k codewords that are not used. These codewords are invalid or illegal.

56. What is a Linear Block Code?

A linear block code is a code in which the exclusive OR (addition modulo-2) of two valid codewords creates another valid codeword.

57. What are Cyclic Codes?

Cyclic codes are special linear block codes with one extra property. In a cyclic code, if a codeword is cyclically shifted (rotated), the result is another codeword.

58. Define Encoder?

A device or program that uses predefined algorithms to encode, or compress audio or video data for storage or transmission use. A circuit that is used to convert between digital video and analog video.

59. Define Decoder?

A device or program that translates encoded data into its original format (e.g. it decodes the data). The term is often used in reference to MPEG-2 video and sound data, which must be decoded before it is output.

60. What is Framing?

Framing in the data link layer separates a message from one source to a destination, or from other messages to other destinations, by adding a sender address and a destination address. The destination address defines where the packet has to go and the sender address helps the recipient acknowledge the receipt.

61. What is Fixed Size Framing?

In fixed-size framing, there is no need for defining the boundaries of the frames. The size itself can be used as a delimiter.

62. Define Character Stuffing?

In byte stuffing (or character stuffing), a special byte is added to the data section of the frame when there is a character with the same pattern as the flag. The data section is stuffed with an extra byte. This byte is usually called the escape character (ESC), which has a predefined bit pattern. Whenever the receiver encounters the ESC character, it removes it from the data section and treats the next character as data, not a delimiting flag.

63. What is Bit Stuffing?

Bit stuffing is the process of adding one extra 0 whenever five consecutive Is follow a 0 in the data, so that the receiver does not mistake the pattern 0111110 for a flag.

64. What is Flow Control?

Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment.

65. What is Error Control ?

Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission.

66. What Automatic Repeat Request (ARQ)?

Error control is both error detection and error correction. It allows the receiver to inform the sender of any frames lost or damaged in transmission and coordinates the retransmission of those frames by the sender. In the data link layer, the term error control refers primarily to methods of error detection and retransmission. Error control in the data link layer is often implemented simply: Any time an error is detected in an exchange, specified frames are retransmitted. This process is called automatic repeat request (ARQ).

67. What is Stop-and-Wait Protocol?

In Stop and wait protocol, sender sends one frame, waits until it receives confirmation from the receiver (okay to go ahead), and then sends the next frame.

68. What is Stop-and-Wait Automatic Repeat Request?

Error correction in Stop-and-Wait ARQ is done by keeping a copy of the sent frame and retransmitting of the frame when the timer expires.

69. What is usage of Sequence Number in Relaible Transmission?

The protocol specifies that frames need to be numbered. This is done by using sequence numbers. A field is added to the data frame to hold the sequence number of that frame. Since we want to minimize the frame size, the smallest range that provides unambiguous communication. The sequence numbers can wrap around.

70. What is Pipelining ?

In networking and in other areas, a task is often begun before the previous task has ended. This is known as pipelining.

71. What is Sliding Window?

The sliding window is an abstract concept that defines the range of sequence numbers that is the concern of the sender and receiver. In other words, he sender and receiver need to deal with only part of the possible sequence numbers.

72. What is Piggy Backing?

A technique called piggybacking is used to improve the efficiency of the bidirectional protocols. When a frame is carrying data from A to B, it can also carry control information about arrived (or lost) frames from B; when a frame is carrying data from B to A, it can also carry control information about the arrived (or lost) frames from A.

73. What are the two types of transmission technology available?

(i) Broadcast and (ii) point-to-point

74. What is subnet?

A generic term for section of a large networks usually separated by a bridge or router.

75. Difference between the communication and transmission.

Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc.

Communication means the meaning full exchange of information between two communication media.

76. What are the possible ways of data exchange?

(i) Simplex (ii) Half-duplex (iii) Full-duplex.

77. What is SAP?

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

78. What do you meant by "triple X" in Networks?

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X".

79. What is frame relay, in which layer it comes?

Frame relay is a packet switching technology. It will operate in the data link layer.

80. What is terminal emulation, in which layer it comes?

Telnet is also called as terminal emulation. It belongs to application layer.

81. What is Beaconing?

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

82. What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

83. What is NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.

NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.

84. What is RAID?

A method for providing fault tolerance by using multiple hard disk drives.

85. What is passive topology?

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don't amplify the signal in any way. Example for passive topology -linear bus.

86. What is Brouter?

Hybrid devices that combine the features of both bridges and routers.

87. What is cladding?

A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

88. What is point-to-point protocol?

A communications protocol used to connect computers to remote networking services including Internet service providers.

89. How Gateway is different from Routers?

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.

90. What is attenuation?

The degeneration of a signal over distance on a network cable is called attenuation.

91. What is MAC address?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

92. Difference between bit rate and baud rate.

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.
  baud rate = (bit rate / N)
  where N is no-of-bits represented by each signal shift.

93. What is Bandwidth?

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

94. What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two categories.

a.) Guided Media: These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.

b.) Unguided Media: This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.

95. What is Project 802?

It is a project started by IEEE to set standards to enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN protocols.

It consists of the following:

1.    802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.

2.    802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.

3.    Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).

4.    802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.

96. What is Protocol Data Unit?

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame).

97. What are the different type of networking / internetworking devices?

1.    Repeater: Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.

2.    Bridges: These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipent and control congestion.

3.    Routers: They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission.

4.    Gateways: They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.

98. What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

99. What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.

100. What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

101. What is the minimum and maximum length of the header in the TCP segment and IP datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

102. What is the range of addresses in the classes of internet addresses?

Class A   -       0.0.0.0   -   127.255.255.255
Class B   -   128.0.0.0   -   191.255.255.255
Class C   -   192.0.0.0   -   223.255.255.255
Class D   -   224.0.0.0   -   239.255.255.255
Class E   -   240.0.0.0   -   247.255.255.255

103. What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.

104. What are major types of networks and explain?

1.    Server-based network: provide centralized control of network resources and rely on server computers to provide security and network administration

2.    Peer-to-peer network: computers can act as both servers sharing resources and as clients using the resources.

105. What are the important topologies for networks?

1.    BUS topology: In this each computer is directly connected to primary network cable in a single line.
Advantages: Inexpensive, easy to install, simple to understand, easy to extend.

2.    STAR topology: In this all computers are connected using a central hub.
Advantages: Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.

3.    RING topology: In this all computers are connected in loop. Advantages: All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.

106. What is mesh network?

A network in which there are multiple network links between computers to provide multiple paths for data to travel.

107. What is difference between baseband and broadband transmission?

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

108. Explain 5-4-3 rule?

In a Ethernet network, between any two points on the network ,there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.

109. What MAU?

In token Ring , hub is called Multistation Access Unit(MAU).

110. What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router.

111. Why should you care about the OSI Reference Model?

It provides a framework for discussing network operations and design.

112. What is logical link control?

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

113. What is virtual channel?

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

114. What is virtual path?

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

115. What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

116. What is traffic shaping?

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

117. What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

118. What is region?

When hierarchical routing is used, the routers are divided into what we will call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

119. What is silly window syndrome?

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

120. What are Digrams and Trigrams?

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.

121. Expand IDEA.

IDEA stands for International Data Encryption Algorithm.

122. What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

123. What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.

124. What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.

125. What is EGP (Exterior Gateway Protocol)?

It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

126. What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

127. What is BGP (Border Gateway Protocol)?

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

128. What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.

129. What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

130. What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

131. What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

132. What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.

133. What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

134. What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.

135. What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.

136. What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.