Tuesday, 25 November 2014

Interview Questions with answer

                                                         
                                        praveensagar4u.blogspot.com

Interview questions(Get it)

* ACTION WORDS: These are words that you should use in your answers that would prove that you would never be satisfied with being a spectator at your job.
      Planned       Implemented      Formulated
      Created       Conceived         Initiated
      Developed   Originated           

* LEADERSHIP WORDS: These are words that should be used throughout the interview to prove that you would rather be a leader than a follower.
      Organized    Built      Presided Over
      Coordinated             Responsible For             Guided
      Supervised   Directed            Gave Direction To
      Managed     Led        

* RESULT WORDS: The use of these words should help to prove that you wanted results and you got them.
      Contributed To         Reduced            Provided For
      Evaluated     Demonstrated That         Collected
      Saved          Achieved           Increased

Dan Johnston from PPR Career shared the following list of frequently asked questions on a job interview, as well as advice on what to be prepared for.

1. Tell me about yourself. Use “Picture Frame Approach”
My name is John Shi. I have been working on web application since 1998, using ASP, JSP, and PHP, in different universities and organization. Currently I am an analyst at AutoZone, responsible of collecting and analyzing business performance data for 130 hub stores. Before that, I spent one and half years of web site development of engineering college at UM. I love the job as a web specialist. I believe my skills in web site, computer programs, and data analyst will help me fit into this challenging job.

Right now I am the hub analyst at supply chain group. In the last 1.5 years at AutoZone, I had worked beyond the expectation from my manager to develop the hub network and improve the hub performance. When I join this position, I was just expected to run a weekly performance reports for these 130 hub stores. However, with my initiatives, I developed numerous tools using SAS, VB/VBA and Web for hub operations. These tools help me make effective job at my position. Extraordinary KPI improvement was observed with my contribution. Moreover, I also took over eCommerce, Vendor, and VDP. With such a rich experience of collaborating with Merch, StDev, StOps, LP, Comm, DI, and ECom, I am ready to join one of the most important departments to carry out a data driven product and price optimization. Actually, I had spent 3 whole years at UC focusing on data driven engineering system. With my degree of IE, I would love to join this excellent group to continue my career at AutoZone.
- Hub analyst - Various department involvements
- 3 years of data driven engineering system research
- PhD of IE in web product optimization
- 10 years of VB/VC/Web programming
- 6 years of SAS development  

Now I have been in this department for one year. I once worked under Maren and recently under Gurcan. I demonstrated a high skill in leading projects such as fog synchronization, store product assortment tool, and demand forecasting. I am energetic and outgoing. In a group, I am cable of getting support from people. I am excited to take this leadership position. I am ready to develop an even stronger team and to provide product assortment decision support tools for the company.

2. Did you bring your resume?
Yes. Be prepared with two or three extra copies. Do not offer them unless you’re asked.

3. What do you know about our organization?
UM is one of the best universities in Mid-South USA. It grows fast in recent years. The Academic Affair Technology office will be a core element to support the whole university to make sure we get best students and faculties and develop the best programs. A web site of AAT will be a portal application for the whole integration. I am sure you are in need of the assistance on architecture and contents organization. I would love to use my skills in web application, data processing and software tools to help you. I am confident to develop a best platform to support the university.   

Because of its direct impact on profits, pricing is one of the most important activities in business. Understanding, managing and improving pricing processes and outcomes is sure to increase margins and revenue.
- Price segmentation / Discrimination
- Lookup and Sales forecasting
- Price impact – Elasticity
- Product assortment MAP

The MAP team is responsible for the processes of MAP product assortment, DNR, and harmonizing with store refresh. We have a powerful forecasting tool, automated assortment decision process, and knowledgeable members to support MAP and DNR processes. The opportunities for this group are to enhance communications between our groups and associated departments in the company, to integrate more between store decisions and category decisions, and mostly importantly, to provide better and more graphically tools for managers.

4. What experience do you have?
Overall I have about 10 years of working on web and software development and programming. Specifically, first, I am familiar with web applications, including ASP, JSP, and PHP and associated DB technologies. I have been managing several active web sites. Second, I am experienced in data manipulations with real applications. So I am familiar with optimization and mathematical programming in real applications. I am able to develop and use statistical models for your academic analysis, migrating the academic results into dynamic web pages.

IE, data driven engineering applications;
5 years of industrial research projects;
10 years of programming in VB/VC/Web;
6 years of SAS development;
one year at AZ.

I had 2 years in AutoZone and 1 year in merchandising. Before coming to Memphis, I led a research team in Cincinnati for industrial and manufacturing optimization projects for 3 years. I am experienced programmer myself. In previous about 10 years, I coordinated and supervised many successful projects. I am ready to lead the team, train subordinates, and develop stronger group, so that we could provide better and more tools for CMs, store operations, supply chain, and VPs.

5. According to your definition of success, how successful have you been so far?
Success is to become expert in the area you like to do.
I have been very successful in schools, as an outstanding research fellow, and as a top ranking student.
Success is to like what you are doing and do an outstanding job.  

6. In your current or last position, what were your most significant accomplishments?
My most significant achievement in my previous job is to combine the data analysis and processing methods with computer technologies. More than 10 engineering data processing projects were accomplished in 3 years. Each of them increases the manufacturing process and system’s performance.
The significance of my current job is I would be able to use various programming tools such as Visual Basic and MapPoint to save time in the assignments. I enjoy being at AutoZone and my manager is very satisfied with my work there.
However, based on my previous experience of graduate RA at UT, I really love working at UT campus as an analyst, so I would be able make full use my education and skills.
However, based on my previous experience of GA at UM, I really love working at UM campus as a web specialist, so I could make full use of my potential and skills.

QOH checking at 9801
10-20% picking save
VB, Telnet; Java

VDP one time fill rate
80% to 90% increase
VB, Communication

Hub utilization
50% to 75-80% increase
Initiative

SPARk (store operations, merchandising, national sales, IT, etc), led to SynchUp
SynchUp (conflict resolution between decisions)
MAP forecast (stabilize it and predict better) and MAP 2.0

7. Had you thought of leaving your present position before? If yes, what do you think held you there?
Each job gains me experience and help me approach my final goal.

I already reached beyond the expectation; and I am ready for next level of analyst.

8. Would you describe a few situations in which your work was criticized?
First time in MIS job, customer requirement analysis was not enough.
I once had difficult to understand what the customer really wanted.
Years of experience trained me very well.

When I first joined company, I lack some knowledge to gut checking some reports before we could send out. I kept it in my mind, I should continue learning and practicing.

9. If I spoke with your previous boss, what would he say are your greatest strengths and weaknesses?
I am real goods at research and software.
Weak: ambitious to do more jobs.

Outstanding job – DJ
Go beyond expectation; get job done. – Maren & Gurcan

10. How would you describe your personality?
Active and positive; good with different people

11. What are your strong points?
Web development, Programming, Problem analysis, reporting
Project management, People coordination, Get-job-done; and Problem solver

12. What are your weak points?
When the time is limited, I once became impatient to finish the work myself to meet the tight deadlines.
Push others to meet the deadline

13. How did you do in school?
I study many courses in statistics and engineering courses. I am also actively involved in societies in our subject, including industrial engineering, healthcare, and biomedical.

14. In your current or last position, what features did you like most? Least?
Most: a very nice manager and a very good working environment.
I like everything about my current position and have acquired and developed a great many skills, but I’m now ready for new challenges and greater responsibilities.”

The current position in a very low grade and salary level; the group didn’t initially expect to do such high level job I did. This MA position needs higher level skills and will mostly use my knowledge and experience.

Opportunity for this position is to communicate with CMs more. We need more involvement with outsiders.

15. What do you look for in a job?
A job can use my skills in programming. A job is related to education. A job I will be able to contribute and improve. A job is of team environment.
By going to school in this topic helped me catch up with the new technology, including the statistic methods, computing algorithms, and management skills too.
Competing with all excellent students and working with knowledge professor helped me learn a lot.

An analyst job can use my skills and experience in data driven system. This MA position is the very one can utilize my experience of 10 years in programming, 6 years of SAS, 5 years of data driven applications, and especially one year at the hub group.

A management position to develop and achieve my potential. My goal is to develop, train and guide a strong MAP team to provide useful assortment decision support tools.

16. How long would it take you to make a meaningful contribution to our firm?
Not long, because of my experience, transferable skills and ability to learn.
I like to take a short time to get familiar with your models and problems.
After that, I will be able to work together with other team members to solve the real cases and improve the work performance.

17. How long would you stay with us?
As long as I feel that I’m contributing, and that my contribution is recognized. I’m looking to make a long term commitment.

18. If you have never supervised, how do you feel about assuming those responsibilities?
If you want to supervise, say so, and be enthusiastic.
A team will be working like a complicated computer program. Each part in it has different functions and has to be working in a workflow manner.
I used to manage many different projects and coordinate various people.
19. Why do you want to become a supervisor?
“To grow and develop professionally, to help others develop, to build a team and to share what I have learned.”

20. What do you see as the most difficult task in being a supervisor?
“Getting things planned and done through others and dealing with different personalities.” Show how you have done this in the past. The habit of time management is different among people.

21. You’ve been with your current employer quite a while. Why haven’t you advanced with him?
“What I like about my present position is that it’s both stable and challenging. But it’s true that I’ve grown about as much as I can in my current position.

22. Why are you leaving your present position?
I am eager to take on more challenges, and I believe I will find them at [hiring company].

I’m not unhappy (at my present employer). However, this opportunity seems to be particularly interesting and I am interested in pursuing it further.

Our office is closing; the whole organization is being reduced in size.

I was not on the market when PPR Career contacted me and explained what you are doing, it peaked my interest.


23. Describe what would be an ideal working environment?
Team work is the key.

24. How would you evaluate your present firm?
Be positive. Refer to the valuable experience you have gained. Don’t mention negatives.

25. Do you prefer working with figures, or with words?
Be aware of what the job requires and position your answer in that context. In many cases it would be both.
Balance between figures and words

I love working with data. Data driven approach was my main job in previous 5-6 years. I developed numerous tools in this area.

Our main aim is to provide clear and meaningful data and figures to CMs, directors, VPs to help them make right decisions. Best parts at Right price.

26. What kinds of people do you find difficult to work with?
I would prefer working with persons who are motivated, team-working, and tend to listen.

27. How would your co-workers describe you?
Refer to your strengths and skills.
Programming + Data processing skills
Like to communicate with people
Have clear schedules

28. What do you think of your boss?
If you like him or her, say so and tell why. If you don’t like him or her, find something positive to say.

29. Why do you want to work in a company of this size? Or this type?
Explain how this size or type of company works well for you, using examples from the past if possible.

PPO (Product and Price Optimization) group’s size is bigger than my current one. I will enjoy team working here.

30. If you had your choice of jobs and companies, where would you go?
This job and this company are very close to what best suits you.

31. Why do you want to work for us?
You feel you can help achieve the company’s objectives, especially in the short run. You like what you’ve learned about the company, its policies, goals and management: “I’ve researched the company and people tell me it’s a good place to work.”

I can help the group maintain the data driven approach. I will help develop more effective tools to enable and implement product assortment and price optimization.

32. What was the last book you read? Movie you saw? Sporting event you attended?
Think this through. Your answer should be compatible with accepted norms.
Book: Prey; Timeline - Michael Crichton
Movie: Cars; Star Gate
Sports: Federer’s tennis

33. What are you doing, or what have you done to reach your career objectives?
Talk about formal courses and training programs.
I took a lot of statistic and software courses.
I was involved in many chances, even including some volunteer opportunities.
I kept building web sites
Know people in AZ and ask

34. What was wrong with your last company?
No company is perfect; it had both strengths and weaknesses.

35. What kind of hours are you used to working?
(Does the person match job and criteria?)
I will say, as many hours as it takes to get the job done.

36. What would you do for us?
Relate past success in accomplishing the objectives which are similar to those of the prospective employer.
- Know data sources – Hub analyst
- Programming – VB/VC/Java
- Data driven optimization – IE post-doc and PhD
- Team working; Inspiring and motivating

I can lead the team
- Support them, Train them and Guide them
- Integrate MAP, store, and forecast
- MAP 2.0 upgrade – close connected with CMs

37. What has your experience been in supervising people?
Give examples from accomplishments.
Cleveland manufacturing productivity project
Find the problem in the manufacturing system
Collected the data / Analyze the data / Statistical testing / Manage 1 master student
Increase the productivity

Projects – SPARk, SynchUp, Demand forecast

38. Are you a good supervisor?
Yes, my people like and respect me personally and professionally. They often comment on how much they learn and develop under my supervision. For example, a dozen of students even wrote letters to thank me for instructing their programming.

39. Did you ever fire anyone? If so, what were the reasons and how did you handle it?
If you haven’t, say so, but add that you could do it, if necessary.

40. How have you helped your company?
Finished X projects; X applications.

22 projects since December

41. What is the most money you ever accounted for? Largest budget responsibility?
Refer to accomplishments. If you haven’t had budget responsibility, say so, but refer to an accomplishment that demonstrates the same skill.

42. What’s the most difficult situation you ever faced on the job?
MPI techniques à computing load
Order fill rates – Call the stores

Synchronization
Demand forecast
DAD forecast stabilization

43. Describe some situations in which you have worked under pressure or met deadlines?
Hong Kong, multiple projects with different skill sets
Detailed and systematical project plans; Organized teams

SynchUp – pressure from other department, IT, and technical issues

44. How do you handle rejection?
I see rejection as an opportunity. I learn from it. When a customer takes a pass, I ask him what we could do to the product, price or service to make it possible for him to say yes. Don’t get me wrong: You’ve got to makes sales. But rejection is valuable, too. It’s a good teacher.”

45. In your present position, what problems have you identified that had previously been overlooked?
Load force profile – Nonlinar; Dbl-exponential curve
Curve fitting – Polynomial functions

VDP ontime (delay)
Hub UT rate
Hub driver hours
New hub proforma

A cople of projects I am working on will be the future development of the group: SynchUp, Forecast, MAP 2.0

46. Give an example of your creativity.
Human lung simulation
Statistical – Save huge computing load

Route analysis – MapPoint VB programming
Hub Report – Macro SAS programming
VDP DVP Report – Excel charts
Hub test – VBA

Include web into MAP
Demand forecasting

47. Give examples of your leadership abilities.
Research project of neural fuzzy tool development at Cincinnati

48. What are your career goals?
Talk first about doing the job for which you are applying.
Your career goals should mesh with the hiring company goals.

Hub network performance <- Hub weekly report
Product Assortment (Fast and Accurate) and Price Optimization (Profit and Stable)

49. What position do you expect to have in two years?
Just say you wish to exceed objectives so well that you will be on a promotable track.

50. What are your objectives?
(How does the person handle stress? What is their confidence level?)

51. Why should we hire you?
This may sound suspicious, negative, or just plain harsh. Actually, it’s a call for help. The employer wants you to help him/her hire you. Keep your response brief. Recap any job requirements the interviewer may have mentioned earlier in the interview, then, point by point, match your skills, abilities and qualifications to those items. Relate a past experience which represents success in achieving objectives which may be similar to those of the prospective employer.

I possess the skills required for this job. And I am ready to start the work.
Data driven application, VB/VBA, Programming, Web = I have all of these with outstanding records.

Because I am the right person you are looking for.

52. You may be over-qualified or too experienced for the position we have to offer.
“A strong company needs a strong person.” An employer will get faster return on investment because you have more experience than required.

When I joined the hub analyst, I was told as over qualified too. But they are so happy now.
I am sure you will find it too if I take this MA position.

Great people generate great service.

53. Why haven’t you found a new position before now?
“Finding the right job takes time. I’m not looking for just any job.”

54. If you could start again, what would you do differently?
No need to be self-revealing. “Hindsight is 20/20; everyone would make some changes, but I’ve learned and grown from all my decisions.”

I am quite satisfied with my records.

55. How much do you expect if we offer this position to you?
I would expect a fair salary based on the job responsibilities, my experience and skills and the market value of the job.


I am just expecting to get a fair salary. I know this PPO group requires the most high level skills and knowledge. I would love to join your extraordinary work and make outstanding contribution like I did before. I am sure in a short time, I will be a key assert in your group. 

                                         praveensagar4u.blogspot.com

Monday, 24 November 2014

Networking Sample Questions

praveensagar4u.blogspot.com
Question Bank

1. Which of the following protocols are examples of TCP/IP transport layer protocols?
a. Ethernet
b. HTTP
c. IP
d. UDP
e. SMTP
f. TCP
2. Which of the following protocols are examples of TCP/IP network access layer protocols?
a. Ethernet
b. HTTP
c. IP
d. UDP
e. SMTP
f. TCP
g. PPP
3. The process of HTTP asking TCP to send some data and make sure that it is received correctly is an example of what?
a. Same-layer interaction
b. Adjacent-layer interaction
c. The OSI model
d. All the other answers are correct.
4. The process of TCP on one computer marking a segment as segment 1, and the receiving computer then acknowledging the receipt of segment 1, is an example of what?
a. Data encapsulation
b. Same-layer interaction
c. Adjacent-layer interaction
d. The OSI model
e. None of these answers are correct.
5. The process of a web server adding a TCP header to a web page, followed by adding an IP header, and then a data link header and trailer is an example of what?
a. Data encapsulation
b. Same-layer interaction
c. The OSI model
d. All of these answers are correct.
6. Which of the following terms is used specifically to identify the entity that is created when encapsulating data inside data link layer headers and trailers?
a. Data
b. Chunk
c. Segment
d. Frame
e. Packet
f. None of these—there is no encapsulation by the data link layer.
7. Which OSI layer defines the functions of logical network-wide addressing and routing?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
e. Layer 5
f. Layer 6
g. Layer 7
8. Which OSI layer defines the standards for cabling and connectors?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
e. Layer 5
f. Layer 6
g. Layer 7
9. Which OSI layer defines the standards for data formats and encryption?
a. Layer 1
b. Layer 2
c. Layer 3
d. Layer 4
e. Layer 5
f. Layer 6
g. Layer 7
10. Which of the following terms are not valid terms for the names of the seven OSI layers?
a. Application
b. Data link
c. Transmission
d. Presentation
e. Internet
f. Session


Fill In The Blanks:
1. Number of links to connect n nodes in a mesh topology is = _______.
2. Mesh Topology is _______ flexible and has a ________ expandability
3. In BUS topology, at each end of the bus is a ____________, which absorbs any signal, removing it from the bus. 
4. In BUS topology, One can easily add any new node or delete any node with-out affecting other nodes; this makes this topology easily _____________. 
5. _________ and ______________ will force a maximum length of shared medium which can be used in BUS topology. 
6. The two alternatives for the operation of the central node in STAR topology are:
__________ and ___________. 
7. In Ring Topology, the links are _____________; that is, data are transmitted in __________ direction only and all are oriented in the same way
8. In Ring Topology, Repeater works in 3 modes: ____________, _____________ and ______________.
9. ___________ topology can be considered as an extension to BUS topology.
10. ______________ is suitable for use in star and ring topologies
11. Coaxial cable is suitable for use in __________ topology.
Solutions:
1. n(n-1)/2
2. not, poor
3. terminator
4. expandable.
5. Delay, signal unbalancing
6. repeater, switch
7. unidirectional, one
8. Listen, Transmit, By-Pass
9. Tree
10. Twisted pair
11. BUS
Short Answer Questions:
Q-1.  List out the advantages and drawbacks of bus topology.
Ans: Advantages:
i) Easy to implement 
ii) It is very cost effective because only a single segment required
iii) It is very flexible
iv) Moderate reliability.
v) Can add new station or delete any station easily (scalable)
Disadvantages:
i) Required suitable medium access control technique.
ii) Maximum cable length restriction  imposed due to delay and signal
unbalancing problem.
Q-2.  List out the advantages and drawbacks of ring topology.
Ans: Advantages:
i) Data insertion, data reception and  data removal can be provided by repeater
ii) It can provide multicast addressing.
iii) Point-to-point links to its adjacent nodes (moderate cost)
Disadvantages:
i) The repeater introduces a delay
ii) The topology fails if any link disconnects or a node fails.
iii) Direct link not provided
iv) It provides complex management

Q-3.  Why star topology is commonly preferred?
Ans: It gives high reliability, more flexible and higher bandwidth. Since there is a central control point, the control of network is easy and priority can be given to selected nodes.
Q-4. Is there any relationship between transmission media and topology?
Ans: Yes, medium should be selected based on the topology. For example, for bus topology coaxial cable medium is suitable, and for ring/star topology twisted-pair or optical fiber can be used.


Fill In The Blanks:
1. The basic question which has to be answered by the medium-access control techniques is “How Goes ________”?
2. In _______________ technique, each node gets a chance to access the medium by rotation.
3. The key issues involved in MAC protocol are - Where and ______ the control is exercised.
4. ‘Where’ refers to whether the control is exercised in a _____________ or ______________ manner.
5. The _______________ techniques can be broadly  categorized into three types; Round-Robin, Reservation and___________.
6. ______________ is an example of centralized control and ______________ is an example of distributed control
Version 2 CSE IIT, Kharagpur 7. In Polling technique, if there is  no data, usually a ______________ message is sent back. 
8. In pure ALOHA, channel utilization, expressed as throughput S, in terms of the offered load G is given by _________ 
9. In slotted ALOHA, a maximum throughput of ________ percent at 100 percent of offered load can be achieved, while it is ______ percentage for pure ALOHA. 
10. _________________ is abbreviated as CSMA/CD and is also known as  .__________
11. To achieve stability in CSMA/CD back off scheme, a technique known as ______________ is used
Solutions:
1. Next
2. token passing
3. How
4. centralized, distributed
5. asynchronous, Contention
6. Polling, token passing
7. poll reject
8. S=Ge-2G
9. 37, 18
10. Carrier Sensed Multiple Access with Collision Detection, Listen-While-Talk .
11. binary exponential back off
Short Answer Questions:
Q-1. In what situations contention based MAC protocols are suitable?
Ans:    Contention based MAC protocols are suitable for bursty nature of traffic under light to moderate load. These techniques are always decentralized, simple and easy to implement.
Q-2.  What is vulnerable period? How it affects the performance in MAC protocols?
Ans: The total period of time when collision may occur for a packet is called vulnerable period. Let, all packets have a fixed duration  λ. Then vulnerable period is 2λ in pure ALOHA scheme and  λ in slotted ALOHA scheme. If vulnerable period is long, probability of the occurrence collision increases leading to reduction in throughput.
Q-3.  How throughput is improved in slotted ALOHA over pure ALOHA?
 Ans: In pure ALOHA vulnerable period is 2λ. 
So, S/G = e-2G  or throughput S = G e-2G , where G is the total number of packets. 
Maximum value of G = 0.5 or maximum throughput Smax = 1/2e.
In slotted ALOHA, vulnerable period is λ    and S/G = e-G  or throughput S = G e-G . Here,
maximum value of G is 1 and maximum throughput Smax = 1/e.
Q-4. What is the parameter ‘a’? How does it affect the performance of the CSMA protocol?
Ans:  The efficiency of CSMA scheme  depends on propagation delay, which is represented by a parameter ‘a’ as defined below.
                            propagation delay
                     a = --------------------------------
                            packet transmission time 
 Smaller the value of propagation delay, lower is the vulnerable period and higher is the efficiency. If propagation delay is zero, collision cannot occur in CSMA scheme. But in practice, there is some delay and depending on the value of  ‘a’ collision occurs.
Q-5.   How performance is improved in CSMA/CD protocol compared to CSMA protocol?
Ans: In CSMA scheme, a station monitors the channel before sending a packet. Whenever a collision is detected, it does not stop transmission leading to some wastage of time. On the other hand, in CSMA/CD scheme, whenever a station detects a collision, it sends a jamming signal by which other station comes to know that a collision occurs. As a result, wastage of time is reduced leading to improvement in performance. 


Fill In The Blanks :
1. The  802.2 standard describes the ____________, which is the upper part of the data link layer. 
2. LLC offers three types services: Unreliable datagram service, ________________ and _______________.
3. IEEE 802 bundle also includes a MAN standard IEEE 802.6 which is also known as ______________.
4. 100Base-T2 means _______________________________
5. 100 Mbps, baseband, long wavelength over optical fiber cable will be abbreviated as ________________
6. Ethernet uses __________ encoding
Answers:
1. LLC (logical link layer)
2. Acknowledged datagram service, Reliable connection oriental service
3. Distributed Queue Dual Bus (DQDB)
4. 100 Mbps, baseband, over two twisted-pair cables
5. 1000Base F
6. Bi-phase Manchester
Short question Answers
Q-1 What are the goals in mind of IEEE 802 committee?
Ans: IEEE 802 committee has few goals in mind, namely
– To promote compatibility
– Implementation with minimum efforts
– Accommodate diverse applications
Q-2.  List the functions performed by the physical layer of 802.3 standard?
Ans.  Functions of physical layer are:
i) Data encoding/decoding (To facilitate synchronization and efficient transfer of signal through the medium).
ii) Collision detection (It detects at the transmit side)
iii) Carrier sensing (Channel access senses a carrier on the channel at both the transmit and receive sides)
iv) Transmit/receive the packets (Frame transmitted to all stations connected to the channel)
v) Topology and medium used (Mediums are co-axial cable, twisted pair and fiber optic cable) 
Q-3.  Why do you require a limit on the minimum size of Ethernet frame?
Ans. To detect collision, it is essential that a sender continue sending a frame and at the same time receives another frame sent by another station. Considering maximum delay with five Ethernet segments in cascade, the size of frame has been found to be 64 bytes such that the above condition is satisfied. 
Q-4.  What are the different types of cabling supported by Ethernet standard?
Ans.  Types of cabling are:
i) 10 BASE 5 - Maximum cable length  is 500 meters using 4” diameter coaxial cable.
ii)  10 BASE 2 - Maximum cable length is 185 meters using 0.25” diameter CATV cable.
iii) 10 BASE T - Maximum cable length  is 100 meters using twisted-pair cable (CAT-3 UTP).
iv) 10 BASE FL - Maximum cable length is 2 Km using multimode fiber optic cable (125/62.5 micrometer).

Fill In The Blanks:
1. Originally, ______________ developed Token Ring network in the ________.
2. A disadvantage of this topology is that it is vulnerable to _________ or _____ failure.
3. Unlike CSMA/CD networks (such as Ethernet), token-passing networks are ________________, which means that it is possible to calculate the maximum time that will pass before any end station will be capable of transmitting.
4. Token Ring frames have two fields that control priority: ___________ and the ___________field.
Version 2 CSE IIT, Kharagpur 5. In Token Ring inside the wire center, _____________ are used to isolate a broken wire or a faulty station.
6. The Mac sublayer in Token BUS consists of four major functions: ____________, the access control machine (ACM), ______________________and  .____________
7. ___________ determines when to place a frame on the bus, and responsible for the maintenance of the logical ring including the error detection and fault recovery.
Answers:
1. IBM, 1970
2. link, station
3. deterministic
4. the priority field, reservation
5. bypass relays
6. the interface machine (IFM), the receiver machine (RxM), the transmit machine (TxM).
7. Access control machine (ACM)
Short question Answers:
Q-1.  What is the advantage of token passing protocol over CSMA/CD protocol?
Ans.     Advantage of token passing protocol over CSMA/CD protocol: 
The CSMA/CD is not a deterministic protocol. A packet may be delivered after many (up to 15) collisions leading to long variable delay. An unfortunate packet may not get delivered at all. This feature makes CSMA/CD protocol unsuitable for real-time applications. On the other hand, token passing protocol is a
deterministic approach, which allows a  packet to be delivered within a known time frame. It also allows priority to be assigned to packets. These are the two key advantages of token passing protocol over CSMA/CD protocol.
Q-2.  What are the drawbacks of token ring topology?
Ans.  Token ring protocol cannot work if a link or a station fails. So, it is vulnerable to link and station failure. 
Q-3.  How the reliability of token ring topology can be improved?
Ans.  Reliability of the ring network can be improved by implementing the ring topology using a wiring concentrator. This allows not only to detect fault, but also to isolate the faulty link/station with the help of a bypass relay. 
Q-4.  What role the active token monitor performs?
Ans. Token ring is maintained with the help  of active token monitor. Any one of the stations has the capability to act as active token monitor, but at a particular instant only one acts as active token monitor. It monitors various error situations such as multiple token, orphan packet, etc, and takes appropriate action to come out of the error situation. 
Fill In The Blanks: 
1. The high speed LANs that have emerged  can be broadly categorized into three types______________, successors of Ethernet and ___________.
2. ATM, fiber channel and the Etherswitches comes under high speed LANs based  on _______________.
3. ______________________ is abbreviated as FDDI.
4. FDDI over copper is referred to as __________________________.
5. The basic topology for FDDI is _____________________.
6. An _____________ provides continuous dual-ring operation if a device on the dual ring fails
7. Each data frame in FDDI carries up to ____________ bytes.
8. FDDI gives fair and equal access to the ring by using a _________ protocol.
9. FDDI implements MAC using three timers namely: ________________,  Token Rotation Timer (TRT) and ___________________
10. Token holding Timer  (THT), which determines .___________________________
11. The frame status (FS) byte is  set by the ____________ and checked by the _______________ station which removes its frame from the ring and generates another token.
12. When the frame returns to the sending  station, that station removes the frame from the ring by a process called ___________.
13. The physical layer is divided into two sub layers - _______ and ______
Solutions.
1. based on token passing, based on switching technology.
2. based on switching technology.
3. Fiber Distributed Data Interface
4. Copper-Distributed Data Interface (CDDI).
5. dual counter rotating rings
6. optical bypass switch
7. 4500
8. timed token
9. Token holding Timer (THT), Valid Transmission Timer (VTT)
10. how long a station may continue once it has captured a token
11. destination, source
12. stripping
13. PMD, PHY
Short Questions: 
Q-1.  In what way the MAC protocol of FDDI differs from that of token ring?
Ans:  In the frame format of FDDI protocol, preamble is eight bytes instead of one byte in token ring. Also token has one additional byte. FDDI can have multiple frames simultaneously, which cannot be present in token ring. Here, the access method is timed token passing. Multiple frames can be transmitted after capturing a token.  First, the entire token is captured and then the data frames are introduced, whereas token ring follows token passing protocol and beginning of token  is converted to the header of a frame.  In case of token ring token is released after receiving the acknowledgement (as the data frame returns after circulating the  ring). On the other hand, in case of FDDI, token is released immediately after sending  data frame, which is known as early token release. 


Q-2.  How FDDI offers higher reliability than token ring protocol?
Ans:  Token ring protocol is applicable in a single ring. Disadvantage of this protocol is that, if one segment of wires fails or a node fails, the protocol cannot work. To increase reliability, dual counter ring topology used in FDDI protocol, where there are two rings, called primary ring and secondary ring. In case  of failure of a node or a fiber link, the ring is restored the by wrapping up the primary ring to the secondary ring. Further improvement in reliability can achieve by using  dual ring of trees and  dual homing mechanism. It will provide multiple paths and if one path fails, another path will be available for passing token or data. 
Q-3 What are the functionalities of a Optical Bypass Switch?
Ans: An optical bypass switch provides continuous dual-ring operation if a device on the dual ring fails. This is used both to prevent ring segmentation and to eliminate failed stations from the ring. The optical bypass switch performs this function using optical mirrors that pass light from the ring directly to the DAS (dual-attachment station) device during normal operation. If a failure of the DAS device occurs, such as a power-off, the optical bypass switch will pass the light through itself by using internal mirrors and thereby will maintain the ring's integrity. When using the OB, you will notice a tremendous digression of your network as the packets are sent through the OB unit.
Q-4 What are the functionalities provided by SMT standard?
Ans: The Station Management (SMT) standard provides services that monitor and control a FDDI station.  SMT include facilities for connection management, node configuration, recovery from error condition, and encoding of SMT frames.
Q-5 Describe various fields in frame format of FDDI?
Ans: Let us have a look at the various fields:
SD: The first byte, after the preamble, of the field is the frame’s starting flag. As in
Token ring these bits are replaced in physical layer by the control codes.
FC: it identifies the frame type i.e. token or a data frame.
Address: the next 2 fields are destination and source addresses. Each address consists of
2-6 bytes.
Data: Each data frame carries up to 4500 bytes.
FCS: FDDI uses the standard IEEE four-byte cyclic redundancy check.
ED: this field consists of half a byte in data frame or a full byte in token frame. This
represents end of the Token.
FS: FDDI FS field is similar to that of Token Ring. It is included only in data/Command
frame and consists of one and a half bytes. 
Fill In The Blanks: 
1. Switched Ethernet gives dedicated 10 Mb/s bandwidth on __________ of its ports.
2. In Ethernet (IEEE 802.3) the topology, though physically is _________ but logically is BUS. i.e. the collision domain of all the nodes in a LAN is   ._________
3. In Switched Ethernet, collision domain is separated. Hub is replaced by a  .________
4. There are two techniques used in the implementation of Ethernet switches: _____________ and ________ 
5. IEEE has designed two categories of Fast Ethernet: ____________ and   .__________
6. 100-Base-X itself is divided into two: __________ and __________ 
7. The Gigabit Ethernet Alliance was formed in ___________ by ______ companies.
8. The GMII is the interface between the ________ layer and the ___________ layer.
9. ________, a sublayer of GMII provides a medium-independent means for the PCS to support various serial bit-oriented physical media.
10. Packet Bursting is an extension of ______________. Packet Bursting is "Carrier Extension plus a ____________".
Solutions:
1. each
2. star, common
3. switch
4. store-and-forward, cut-through
5. 100Base-X, 100Base-T4
6. 100Base-TX, 100base-FX.  
7. May 1996, 11
8. MAC, Physical
9. PMA (Physical Medium Attachment)
10. Carrier Extension, burst of packets
Short Questions: 
Q-1. Explain the basic difference between IEEE 802.3 and switched Ethernet, as far as implementation is concerned.
Ans: In Ethernet (IEEE 802.3) the topology, though physically is start but logically is BUS. i.e. the collision domain of all the nodes in a LAN is common. In this situation only one frame can send the frame, if more than one station sends the frame, there is a collision. 
In Switched Ethernet, this collision domain is separated. Hub is replaced by a switch, a device that can recognize the destination address and can route the frame to the port to which the destination station is connected, the rest of the media is not involved in the transmission process. The switch can receive  another frame from another station at the same time and can route this frame to its own final destination.
Q-2. Explain the two techniques for implementing Ethernet switches. 
Ans: There are two techniques used in the implementation of Ethernet switches:  storeand-forward and  cut-through. In the first case, the entire frame is captured at the incoming port, stored in the switch’s memory, and after an address lookup to determine the LAN destination port, forwarded to  the appropriate port. The lookup table is automatically built up. On the other hand,  a cut-through switch begins to transmit the frame to the destination port as soon as it decodes the destination address from the frame header.
Store-and-forward approach provides a greater level of error detection because damaged frames are not forwarded to the destination port. But, it introduces longer delay of about 1.2 msec for forwarding a frame and suffers  from the chance of loosing data due to reliance on buffer memory. The cut-through switches, on the other hand, has reduced latency but has higher switch cost.
Q-3. What are the different categories of Fast Ethernet?
Ans: IEEE has designed two categories of Fast Ethernet: 100Base-X and 100Base-T4. 100Base-X uses two cables between hub and the station while 100Base-T4 uses four. 100-Base-X itself is divided into two: 100Base-TX and 100base-FX.   * 100 BASE-T4: This option is designed to avoid overwriting. It is used for half-duplex communication using four wire-pairs of the existing category 3 UTP cable, which is already available for telephone services in homes/offices. Two of four pairs are bi-directional; other two are
unidirectional. This means that there are 3 pairs to be used for carrying data, in each direction (2 bi-directional and 1 unidirectional). Because 100Mbps data cannot be handled by voicegrade UTP, this specification splits the 100 Mbps flow into three 33.66Mbps flow.
*100 BASE TX: This option uses two category 5 UTP or two shielded (STP) cable to connect a station to hub. One pair is used to carry frames from the hub to the station and other to  carry frames from station to hub. Encoding is 4B/5B to handle 100  Mbps; signaling is NRZ-I. The distance between station and hub should be less than 100 meters.
  *100 BASE FX: This option uses two Fiber optic cables, one carry frames from station to hub and other from hub to station. The encoding is 4B/5B and signaling in NRZ-I. the distance between station and hub should be less than 2000 meters.
Q-4. What are the Objectives of The Gigabit Ethernet Alliance?
Ans: The objectives of the alliance are: 
• supporting extension of existing Ethernet and Fast Ethernet technology in response to demand for higher network bandwidth. 
• developing technical proposals for the inclusion in the standard 
• establishment of inter-operability test procedures and processes 
Q-5. Explain GMII (Gigabit Media Independent Interface) in brief.
Ans: The GMII is the interface between the MAC layer and the Physical layer. It allows any physical layer to be used with the MAC layer. It is an extension of the MII (Media Independent Interface) used in Fast Ethernet. It uses the same management interface as MII. It supports 10, 100 and 1000 Mbps data rates. It provides separate 8-bit wide receive and transmit data paths, so it can support both full-duplex as well as half-duplex operation. 
The GMII provides 2 media status signals: one indicates presence of the carrier, and the other indicates absence of collision. With the GMII, it is possible to connect various media types such as shielded and unshielded twisted pair, and single-mode and multi mode optical fiber, while using the same MAC controller. It has three sub-layers namely: PCS (Physical Coding Sublayer), PMA (Physical Medium Attachment) and PMD (Physical Medium Dependent).




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