Subject Code / Name:EC2352 COMPUTER NETWORKS

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

SUB.CODE : CS1302 BRANCH / YEAR / SEM: ECE / III / VI

SUB.NAME : COMPUTER NETWORKS By : P.Raja Pirian. M.E.,M.B.A.,

UNIT – I DATA COMMUNICATION

PART A

1. List the advantages of star topology? (AU –ND 2009)-1 Less expensive than mesh topology Easy to install and reconfigure due to only one link and one I/O part to connect it to any

number of others. Robustness Easy fault identification and fault isolation.

2. What is peer to peer process? (AU –ND 2009) -1 Between machines layer-x on one machine can communicate with layer-x of another machine. The processes on each machine that communicate at a given layer are called peer to peer process.

3. What is the required bit rate of the channel? Assume we need to download text documents at the rate of 100 pages per minute. (AU –ND 2010) -1

Bit rate is the number of bits sent in 1s, expressed in bits per second (bps). A page is an average of 24 lines with 80 characters in each line. If we assume that once character requires 8 bits, the bit rate is 100 x 24 x 80 x 8 = 1,636,000 bps = 1,636 Mbps.

4. What is the position of the transmission media in the OSI or the internet model? (AU –ND 2010) -1

(i) Transmission media are actually located below the physical layer and are directly controlled by the physical layer. That is transmission media belong to layer zero.

Figure :1 Transmission Medium And Physical Layer.5. For ‘n’ devices in a network, what is the number of cable links required for a mesh and ring topology. (AU –ND 2011) -1 ( i) Mesh topology – n (n-1)/2 (ii)Ring topology – n6. What is mean by data communication? (AU –ND 2011) -1

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS Data communication is the exchange of data (in the form of 1s and 0s) between two devices via some form of transmission medium (such as a wire cable).7. What is TCP/IP? (AU –ND 2012) -1

1. The second transport layer protocol is called Transmission Control Protocol.2. This is process to process, connection oriented, and reliable transport protocol.3. TCP uses error and flow control mechanism.

8. Compare datagram networks with virtual circuit subnets. (AU –ND 2012) -1 Virtual Circuit Packet Switching

1. Virtual circuits allow packets to contain circuit number instead of full destination address so less router memory and bandwidth require. Thus cost wise it is cheaper.

2. Virtual circuit requires a setup phase, which takes time and consume resources. 3. Virtual circuit has some advantages in avoiding congestion within the subnet because resources

can be reserved in advance, when the connection is established.4. A virtual circuit is a implementation of connection oriented service.

Datagram circuits:1. Datagram circuits allow packets to contain full address instead of circuit number so each packet

has significant amount of overhead, and hence wasted band width. Thus it is costly.2. Datagram circuit does not require setup phase, so no resources are consumed.3. In datagram circuit, a more complicated procedure is required to determine where the packet

goes. In a datagram subnet, congestion avoidance is more difficult.4. The loss or fault on communication line can be easily compensated in datagram circuits.

Datagram allows the router to balance the traffic throughout the subnet, since router can be changed halfway through a connection.

9. List the advantages and disadvantages of the mesh technology. (AU –AM 2010) -1Advantages:

(i) Use of dedicated links (ii) Robust (iii) fault identification and fault isolation easy.Disadvantages:

1. Installation and reconnection are very difficult.2. Sheer bulk of the wiring can be greater than the available space.

3. Hardware requirement is expensive10. Compare multipoint and point-to-point connection. (AU –AM 2010) -1

Point-to-point connections are typically used to connect two systems together over a wide area network (WAN). Each end of the connection has a unique IP address. Addresses are used up just to connect two systems. Multipoint protocols are characterized by a physical medium that connects to all machine and where all connection is heard by all stations.

11. Why are protocols needed? . (AU –MJ 2012) -1In networks, communication occurs between the entities in different systems. Two entities cannot just send bit streams to each other and expect to be understood. For communication, the entities must agree on a protocol. A protocol is a set of rules that govern data communication.

12. Define step index in fiber optics. (AU –MJ 2012) -1Step-index fibers have a uniform core with one index of refraction, and a uniform cladding with a smaller index of refraction

13. List out the five components of data communication system. (AU –AM 2010) -1 (i) Message (ii) Sender (iii) Receiver (iv) Transmission medium (v) Protocol

14. Differentiate: Intranet and Internet. (AU –AM 2010) -1By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS Intranet: An intranet is a set of networks that are under the control of a single administrative entity. The intranet uses the IP protocol and IP-based tools such as web browsers and file transfer applications. Internet: When two or more networks connected in the World Wide Web

15. List the four basic Network topologies. (AU –AM 2011) -1 (i) Mesh (ii) Star (iii) Bus (iv) Ring 16. Distinguish between ADSL and SDSL. (AU –AM 2011) -1

S.no ADSL (Asymmetric DSL) SDSL (Symmetric DSL)

1. Provide asymmetric communication-higher speed in the downstream communication than upper stream communication.

Provides full duplex symmetric communication

2 Down stream rate:1.5-6.1 Mbps Down stream rate :768kbps

3 Up stream rate:16-640kbps Up stream rate: 768kbps

4 Line code:DMT Line code:2BIQ17. Differentiate guided and unguided transmission medium. (AU –MJ2013) -1

S.NSl.NO Guided Media Unguided Media

1. The signal energy propagates within the guided media .i.e. through wires

The signal energy propagates through air

2 It is mainly suited for point to point line configurations

It is mainly used for broadcasting purpose

3 The signal propagates in the form of voltage, current or photons

The signal propagates in the form of electromagnetic waves.

4 Examples of guided media are:-Twisted Pair Cable, Co-axial Cable, Optical Fiber Cable

Examples are: Microwave or Radio Links, Infrared

18. State the role of Digital Subscriber line. (AU –MJ 2013) -11. Digital Subscriber Line (also known as Digital Subscriber Loop) is a technology that transports

high-bandwidth data, such as multimedia, to service subscribers over ordinary twisted pair copper wire telephone lines.

2. A DSL line can carry both data and voice signals and the data part of the line is continuously connected. Digital Subscriber Line technology assumes that digital data does not require change into analog form and back.

3. Digital data is transmitted to the system directly in digital data form, allowing wider bandwidth for transmission. Though, the signal can also be separated so that some of the bandwidth is used to transmit an analog signal allowing users to use telephone and computer simultaneously on the same line.

19. List the layers in the OSI model that handle end to end connection. ( (AU –AP 2009) -1(i) Physical layer (ii) Data link layer (iii) Network layer (iv) Transport layer(v)Session layer (vi) Presentation layer (vii) Application layer

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS20. What are the three criteria necessary for an effective and efficient network?

The most important criteria are performance, reliability and security.(i)Performance of the network depends on number of users, type of transmission medium, and the capabilities of the connected h/w and the efficiency of the s/w. (ii)Reliability is measured by frequency of failure, the time it takes a link to recover from the failure and the network’s robustness in a catastrophe.(iii)Security issues include protecting data from unauthorized access and viruses.

21. What are the three fundamental characteristics determine the effectiveness .of the data communication system?

The effectiveness of the data communication system depends on three fundamental characteristics:(i) Delivery : The system must deliver data to the correct destination.(ii) Accuracy : The system must deliver data accurately.(iii)Timeliness : The system must deliver data in a timely manner.

22. What are the advantages of distributed processing?Advantages of distributed processing include (i)Security/encapsulation (ii) Distributed databases (iii) Faster problem solving (iv) Security through redundancy and collaborative processing.

23. Why are standards needed?Co-ordination across the nodes of a network is necessary for an efficient communication. If there are no standards, difficulties arise. A standard provides a model or basis for development to which everyone has agreed.

24. What is the difference between a passive and an active hub?An active hub contains a repeater that regenerates the received bit patterns before sending them out. A passive hub provides a simple physical connection between the attached devices.

25. Distinguish between peer-to-peer relationship and a primary-secondary relationship.(i) Peer-to-peer relationship: All the devices share the link equally.(ii)Primary-secondary relationship: One device controls traffic and the others must transmit through it.

26. Assume 6 devices are arranged in a mesh topology. How many cables are needed? How many ports are needed for each device?

(i)Number of cables=n (n-1)/2=6(6-1)/2=15(ii)Number of ports per device=n-1=6-1=5

27. Group the OSI layers by function.The seven layers of the OSI model belonging to three subgroups. Physical, data link and network layers are the network support layers; they deal with the physical aspects of moving data from one device to another. Session, presentation and application layers are the user support layers; they allow interoperability among unrelated software systems. The transport layer ensures end-to-end reliable data transmission.

28. What are header and trailers and how do they get added and removed?(i) Each layer in the sending machine adds its own information to the message it receives from the layer just above it and passes the whole package to the layer just below it. (ii)This information is added in the form of headers or trailers. Headers are added to the message at the layers 6,5,4,3, and 2. A trailer is added at layer2. (iii)At the receiving machine, the headers or trailers attached to the data unit at the corresponding sending layers are removed, and actions appropriate to that layer are taken.

29. The transport layer creates a communication between the source and destination. What are the three events involved in a connection?

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSCreating a connection involves three steps: (i) Connection establishment, (ii)Data transfer and (iii)Connection release.

31. How does NRZ-L differ from NRZ-I?(i)In the NRZ-L sequence, positive and negative voltages have specific meanings: positive for 0 and negative for 1. (ii)In the NRZ-I sequence, the voltages are meaningless. Instead, the receiver looks for changes from one level to another as its basis for recognition of 1s.

32. What are the functions of a DTE? What are the functions of a DCE?(i)Data Terminal Equipment is a device that is an information source or information sink. It is connected to a network through a DCE. (ii)Data Circuit-terminating Equipment is a device used as an interface between a DTE and a network.

33. What does the electrical specification of EIA-232 describe?The electrical specification of EIA-232 defines that signals other than data must be sent using OFF as less than -3 volts and ON as greater than +3 volts. The data must be transmitted using NRZ-L encoding.

34. Discuss the mode for propagating light along optical channels.There are two modes for propagating light along optical channels, multimode and single mode.(i)Multimode: Multiple beams from a light source move through the core in different paths.(ii)Single mode: Fiber with extremely small diameter that limits beams to a few angles, resulting in an almost horizontal beam.

35. What is refraction?The phenomenon related to the bending of light when it passes from one medium to another.

36. List out the advantages and drawbacks of bus topology. Advantages:

1. Easy to implement 2. It is very cost effective because only a single segment required 3. It is very flexible 4. Moderate reliability. 5. Can add new station or delete any station easily (scalable)

Disadvantages: 1. Required suitable medium access control technique. 2. Maximum cable length restriction imposed due to delay and signal

unbalancing problem. 37. List out the advantages and drawbacks of ring topology.

Advantages: 1. Data insertion, data reception and data removal can be provided by repeater 2. It can provide multicast addressing. 3. Point-to-point links to its adjacent nodes (moderate cost)

Disadvantages: 1. The repeater introduces a delay 2. The topology fails if any link disconnects or a node fails. 3. Direct link not provided 4. It provides complex management

38. Why star topology is commonly preferred? 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.

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS39. Is there any relationship between transmission media and topology?

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.

PART B :

1. List the functions of OSI layers? Explain(AU –ND 2009, AU –ND 2011, AU –ND 2012, AU –AM 2010, AU –AM 2011, AU –MJ 2012)-6 ( 16)

List of Layers (2) Functions of 7 Layers (14)

2. Explain in detail about the types of topologies. (AU –ND 2009, (AU –AM 2010) -2 (16) Introduction (4) Types - Star, Bus, Ring, Mesh (12)

3. List four properties by which transmission media can differ. (AU –ND 2010) -1 (8)

4. Three packet switching networks each contain n nodes. The networks has a star topology with central switch, a ring respectively and third is fully interconnected with a wire form every node to othernode. What are the best, average and worst case transmission paths in hops?

(AU–ND 2010)-1 (12)5. Explain about coaxial cable and fiber optics media for communication. (AU–ND 2010)-1 (8)

Coaxial cable (4) Fiber optics cable (4)

(i) Explain about transmission modes available for data flow. (AU –ND 2010) -1 (4) (ii) Explain the categories of networks. (AU –ND 2010) -1 (4)

6. Describe the circuit switched networks, data gram networks and cable networks with suitable diagrams. (AU –ND 2011) -1 (16)

Circuit switched networks (4) Data gram networks (4) Cable networks (4) Diagram (4)

7. Explain types of switching networks and mention its advantages and disadvantages.(AU –ND 2012) -1 (16)

Circuit switched networks (4) Data gram networks (4) Cable networks (4) Advantages and Disadvantages (4)

8. Write a short note on various types of transmission media, highlighting their merits and demerits. (AU –AM 2010) -1 (8)

Guided Media (4) Unguided Media (4)

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS9. Briefly explain the different types of packet switching techniques with suitable networks. Write

each of its advantages and disadvantages. (AU –AM 2011) -1 (16) Virtual Circuit Packet Switching with advantages & Disadvantages (8) Datagram Packet Switching with advantages & Disadvantages (8)

10. Explain the TCP/IP reference model with a neat sketch. (AU–JM 2013) -1 (8) Diagram (4) Explanation (4)

11. Compare the performance of TCP/IP and ISO/OSI reference model (AU–JM2013) -1 (8)

12. Explain in detail about Network dependent and network independent layers of OSI reference model. (AU –JM 2013)-1 (16)

Network dependent layers of OSI reference model. (8) Network independent layers of OSI reference model. (8)

13. Describe the key elements of protocols and the standards. (16)

14. With relevant examples differentiate between simplex, half duplex and full duplex

communication. (16)

UNIT-II DATA LINK LAYER

PART A

1. What are the types of frames available in high level Data link Control? (AU–ND 2009) -11. Information Frames (I-Frames) 2. Supervisory Frames (S-Frames) 3. Unnumbered Frames(U-Frames)

2. What is token ring? (AU – ND 2009) -11. Token ring is a LAN protocol standardized by IEEE and numbered as IEEE 802.4.2. In a token ring network, the nodes are connected into a ring by point-to-point links. 3. It supports data rate of 4 & 16 Mbps. 4. Each station in the network transmits during its turn and sends only one frame during each

turn. 5. The mechanism that coordinates this rotation is called Token passing. 6. A token is a simple placeholder frame that is passed from station to station around the ring.

A station may send data only when it has possession of the token. 3. Define framing and reason for its need. (AU –ND 2010) -1

(i) Framing is the data link layer separates a message from one source to a destination, or from other message to other destinations, by adding a sender address and a destination address.

(ii) The destination address defines where the packet is to go, the sender address helps the recipient acknowledge the receipt.

4. Compare piconet and scatternet. (AU –ND 2010) -1(i) Piconet : A Bluetooth network is called a piconet , or a small net. The communication between the primary and the secondary can be one-to-one or one-to-many.

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS

(ii) Scatternet: Piconets can be combined to form what is called a scatternet.

5. What is the purpose of hamming code? (AU –MJ 2012) -1A hamming code can be designed to correct burst errors of certain lengths. So thesimple strategy used by the hamming code to correct single bit errors must be redesigned to be applicable for multiple bit correction.

6. Compare Goback N ARQ with stop and wait ARQ. (AU –AP 2010) -1(i) Goback N ARQ: Sender keeps copy of up to WS outstanding packets, k-bit sequence number, SN in packet header. When the receiver notices a missing/erroneous frame it discards ALL frames with greater SNs and sends no ACK .

(ii)Stop and Wait ARQ:Sender A transmits a packet, then wait, If frame is error-free, B sends acknowledgement (ACK), else, B sends a negative acknowledgement (NACK),- Sender A sends next packet or retransmit when it receives ACK or NACK.8. What are the problems of interconnecting various networks? (AU –ND 2011) -1

1. Total Bandwidth 2. Link Bandwidth 3. Message Latency 4. Bisection Bandwidth 5 .Number of connections per node6. Number of links as a function of the number of nodes 7.Diameter

9. Define flow control & error control. (AU –AM 2011) -1 Flow control refers to a set of procedures used to restrict the amount of data. The sender can

send before waiting for acknowledgment. Error Control refers to primarily to methods of error detection and retransmission.

10. Define Bluetooth. (AU –ND 2012) -Bluetooth is a wireless LAN technology designed to connect devices of different function such as telephone, notebooks, computers (desktop and laptop), cameras, printers, coffee makers and so on. Applications: wireless mouse or keyboard, monitoring device, security device.

11. Why Ethernet is said to be a 1-persistent protocol? (AU –ND 2012) -1

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSEthernet is said to be a 1 persistent protocol because an adaptor with a frame to send transmits with probability 1 whenever a busy line goes idle

12. What are the responsibilities of data link layer? (AU –AM 2010) -1Specific responsibilities of data link layer include the following.a) Framing b) Physical addressing c) Flow controld) Error control e) Access control

13. Which ARQ mechanism utilizes pipeling? (AU –AM 2010) -1GO – Back- N mechanism utilizes pipeling

12. How is repeater different from an amplifier? (AU –AM 2011) -1A repeater is an electronic device that receives a network signal, cleans it of unnecessary noise, and regenerates it. The signal is retransmitted at a higher power levelAmplifier is an electronic circuit that increases the power of an input signal.

13. What is the purpose of network interface card? (AU –AM 2013) -1 Each station on an Ethernet network has its own network interface card. The NIC fits inside the station and provides the station with a 6-byte physical address.

14. What are Virtual LANs? (AU –AM 2013) -1(i)A virtual (or logical) LAN is a local area network with a definition that maps workstations on some other basis than geographic location (for example, by department, type of user, or primary application). (ii)The virtual LAN controller can change or add workstations and manage load balancing and bandwidth allocation more easily than with a physical picture of the LAN. Network management software keeps track of relating the virtual picture of the local area network with the actual physical picture.

16. What is SONET? SONET that is used as a transport network to carry loads from other WANs.The different Layers available in SONET are listed below:

(i) Photonic Layer (ii)Section Layer (iii)Line Layer (iv)Path Layer 17. Define bridges?

Bridge is nothing but a switch that is used to forward packets between shared –media LANs such as Ethernet

18. What is redundancy?It is the error detecting mechanism, which means a shorter group of bits or extra bits may be appended at the destination of each unit.

19. List out the available detection methods.There are 4 types of redundancy checks are used in data communication.a) Vertical redundancy checks (VRC).b) Longitudinal redundancy checks (LRC).c) Cyclic redundancy checks (CRC).d) Checksum.

21. Write short notes on error correction.It is the mechanism to correct the errors and it can be handled in 2 ways.a) When an error is discovered, the receiver can have the sender retransmit the entire data unit.b) A receiver can use an error correcting coder, which automatically corrects certain errors.

19. What is a buffer?Each receiving device has a block of memory called a buffer, reserved for storing incoming data until they are processed.

20. Mention the categories of flow control.There are 2 methods have been developed to control flow of data across communication links.a) Stop and wait- send one from at a time. b) Sliding window- send several frames at a time.

PART BBy : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS1. Explain the classification of ETHERNET. (AU –ND 2009) -1 (16)

Standard EthernetFast EthernetGiga Byte EthernetTen Giga byte Ethernet

2. Describe the collision avoidance mechanism used in 802.11 wireless LAN. (AU –ND 2010)-1 (16) Diagram Explanation

3. Write down the sender and receiver algorithm for Go-Back-N data link protocol. (AU –ND 2010)-1 (8)

Algorithm Explanation

4. Explain HDLC and explain it in detail. (AU–ND 2011)-2 (16)

Definition Diagram Explanation

5. Discuss in detail about standard Ethernet and fast Ethernet. (AU–ND 2011)-2 (16)

Diagram Explanation

6. Explain the flow and error control mechanism in data link control. (AU–ND 2011)-1 (16) Diagram Explanation

7. Write briefly about blue tooth technology. List the application and limitation. (AU–ND 2011)-2 (16)

Definition Diagram Explanation Application

8. Describe in detail the architecture and layers of ATM (AU –ND 2010)-1 (16) Definition Diagram Explanation

9. Discuss the sliding window protocol in detail. (AU–AM 2010,AU –MJ 2013)-2 (8) Definition Diagram Explanation

10. Explain two problems in 802.11 MAC sub layer protocol. . (AU –AP2010)-1 (8)

11. Discuss any two error correction techniques used in wireless links. . (AU –AM 2010)-1 (8) Block coding Minimum distance

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS Retransmission

12. What is CDMA/CD how does it work? Distinguish between 1-persistent and non persistent CSMA. (AU –AP 2011)-1 (8)

CDMA / CD Definition Working method Difference between 1-persistant and non persistent CSMA

13. With neat diagram explain in detail about the stop and wait protocol in detail. (AU –MJ 2013)-1 (8)

Diagram Explanation of Stop and wait Protocol

14. Compare the standard Ethernet, fast Ethernet, gigabit Ethernet and ten-gigabit Ethernet. (AU –MJ 2013)-1 (8)

15. Discuss about piconet and scatter net with diagrams. (AU –MJ 2013)-1 (8) Piconet Explanation with digram Scatternet Explanation with diagram

UNIT III NETWORK LAYER

PART A

1. What is the network address? (AU –ND 2009)-11. A network address serves as a unique identifier for a computer on a network. 2. When set up correctly, computers can determine the addresses of other computers on the

network and use these addresses to send messages to each other.3. Compare connection less and connection oriented service. (AU –AM 2010, AU –ND 2010)-2

S.No.  Characteristics Connectionless Service  Connection Oriented Service

1. Example of Protocol UDP (User Datagram Protocol)TCP (Transmission control protocol).

2. General Description

Simple, high-speed, low functionality "wrapper" that interfaces applications to the network layer.

Full-featured protocol that allows applications to send data reliably without worrying about network layer issues.

3. Connection setupData is sent without setup i.e. connectionless.

Connection must be established p'rior transmission.

4.Data interface to application

Message-based ; data is sent in discrete packages by the applications.

Stream-based ; data is sent by the application with no particular structure.

5.Reliability and acknowledgments

Unreliable, best efforts delivery without acknowledgments

Reliable delivery of messages; all data is acknowledged.

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS

3. What is classless addressing? (AU –AM 2010)-1To overcome address depletion. No classes, but the address are still granted in blocks. The size of the block (the number of addresses) varies based on the nature and size of the entity.

4. What are the responsibilities of network layer. (AU –AM 2010,AU –MJ 2012)-2The network layer is responsible for the source-to-destination delivery of packet across multiple network links. The specific responsibilities of network layer include the following:

• Logical addressing. • Routing.5. What is the function of router? Define routers. (AU –MJ 2012, AU –ND 2009)-2

(i)DSAP SSAP Control Information Routers relay packets among multiple interconnected networks. (ii)They Route packets from one network to any of a number of potential destination networks on Internet routers operate in the physical, data link and network layer of OSI model.

6. What is the function of RIP message? (AU –ND 2010)-1(i)RIP-RoutingInformationProtocol. RIP is a dynamic, distance vector routing protocol and was developed for smaller IP based networks. As mentioned earlier, RIP calculates the best routebasedonhopcount. (ii)Versions:RIPv1,andRIPv2.RIPv1: RIP version 1 is among the oldest protocols.

7. Compare switch with hub. (AU –ND 2011)-1

S.no Switch Hub

1Switch is a layer-2 device, in this data transmission in the form of frames.

Hub is a layer-1 device, in this data transmission in the form of bits.

2SWITCH is layer 2 device which breaks collision domain.ie every device connected to the switch has the equal bandwidth.

HUB is layer 1 device which does not breaks collision domain.ie if more devices are added the bandwith will be shared.

3 It transmit data only to the destination port It is a multiple-port repeaterany signals send.

8. Write the keys for understanding the link state routing. (AU –ND 2011)-1 • Knowledge about the neighborhood. • Routing to all neighbors. • Information sharing when there is a range.9. Define ICMP. (AU –ND 2012)-1 (i)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. (ii) It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

10. Write the keys for understanding the distance vector routing. . (AU –ND 2012)-1The three keys for understanding the algorithm are

1. Knowledge about the whole networksBy : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS2. Routing only to neighbors3. Information sharing at regular intervals

11. State the duties of network layer. (AU –AM 2010)-1(i) Responsible for the source-to-destination delivery of a packet.(ii)Logical addressing(iii)Routing

12. Define geographic routing. (AU –AM 2010)-1Geographical routing uses a node’s location to discover path to that node

1. Nodes know their own geographical location2. Nodes know their 1-hop neighbors-Routing destinations are specified geographically

(a location, or a geographical region)3. Each packet can hold a small amount of routing information.

13. Find the class of each address. (AU –AM 2011)-1(a) 00000001 00001011 00001011 11101111

The first bit is 0. This is a class A address.(b) 14.23.120.8

The first byte is 14 (between 0 and 127), the class is A14. Draw the general format of ICMP. (AU –AM 2011)-1

15.Why IPv6 preferred over than IPv4? (AU –AM 2013)-1(i) Larger address space (ii) Better header format (iii) New options(iv)Allowance for extention (v) Support for resource allocation (vi)Support for more security

16.What is the use of network address translation? (AU –AM 2013)(i) NAT- enables a user to have a large set of addresses internally and one address, or a small set of addresses, externally.(ii) The traffic inside can use the large set, the traffic outside, the small set

17. What are the network support layers and the user support layers?(i)Network support layers:The network support layers are Physical layer, Data link layer and Network layer. These deals with electrical specifications, physical connection, transport timing and reliability.(ii)User support layers:The user support layers are: Session layer, Presentation layer, Application layer. These allow interoperability among unrelated software system.

18. With a neat diagram explain the relationship of IEEE Project to the OSI model?The IEEE has subdivided the data link layer into two sub layers:* Logical link control (LLC)* Medium access control (MAC)

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSLLC is non-architecture specific. The MAC sub layer contains a number of distinct modules, each carries proprietary information specific to the LAN product being used.

19. What are the functions of LLC?The IEEE project 802 models take the structure of an HDLC frame and divide it into 2 sets of functions. One set contains the end user portion of the HDLC frame – the Other layers Network Data link Physical Other layers Network,Logical Link Control,Media Access Control,Physical logical address, control information, and data. These functions are handled by the IEEE 802.2 logical link control (LLC) protocol.

20. What are the functions of MAC?MAC sub layer resolves the contention for the shared media. It contains synchronization, flag, flow and error control specifications necessary to move information from one place to another, as well as the physical address of the next station to receive and route a packet.

21. What is protocol data unit?The data unit in the LLC level is called Protocol Data Unit (PDU). It contains fourfields.

1. Destination Service Point Address (DSAP) 2.Source Service Access Point

3. Control field 4.Information field22. Define Routers.

DSAP SSAP Control Information Routers relay packets among multiple interconnected networks. They Route packets from one network to any of a number of potential destination networks on Internet routers operate in the physical, data link and network layer of OSI model.

23. What is meant by hop count?The pathway requiring the smallest number of relays, it is called hop-count routing, in which every link is considered to be of equal length and given the value one.

24. How can the routing be classified?The routing can be classified as,

1. Adaptive routing 2.Non-adaptive routing.25. What is time-to-live or packet lifetime?

As the time-to-live field is generated, each packet is marked with a lifetime, usually the number of hops that are allowed before a packet is considered lost and accordingly, destroyed. The time-to-live determines the lifetime of a packet.

26. What is meant by brouter?A brouter is a single protocol or multiprotocol routers that sometimes act as a router and sometimes act as a bridge.

27. Write the keys for understanding the distance vector routing.The three keys for understanding the algorithm are

1. Knowledge about the whole networks2.Routing only to neighbors

3. Information sharing at regular intervals28. Write the keys for understanding the link state routing.

The three keys for understanding the algorithm are1. Knowledge about the neighborhood. 2. Routing to all neighbors.3. Information sharing when there is a range.

29. How the packet cost referred in distance vector and link state routing?In distance vector routing, cost refer to hop count while in case of link state routing, cost is a weighted value based on a variety of factors such as security levels, traffic or the state of the link.

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSPART B

1. Describe distance vector routing. (AU –ND 2009, AU –MJ 2012)-2 (8) Definition Diagram Explanation Application

2. Compare the distance vector and the link state routing protocol. (AU –ND 200,)-2 (8)

3. Explain in detail about Link state routing protocol. (AU –AM 2010, AU –MJ 2012)-2 (8) Definition Diagram Explanation

4. Explain about IP addressing methods . (AU –AM 2010,)-1 (8) Definition Explanation

5. State the advantages of IPv6 over IPv4. (AU –ND 2010)-1 (8) Advanatges of Pv 6 Advanatges of Pv 4

6. What is subnetting? Discuss. Also state which classes of IP address can be subnetted. (AU –ND 2010)-1 (8)

Definition Explanation

7. What is subnet masking? Discuss. (AU –ND 2010)-1 (8) Definition Explanation

8. Explain about internet protocol-IPv4 and IPv6. (AU –ND 2011, AU –ND 2012)-2 (8) Definition Explanation

9. Explain about routing-unicast, multicast routing protocols. (AU –ND 2011)-1 (8) Definition Diagram Explanation

10. Write short notes on BOOTP. (AU –ND 2012)-1 (8)

11. How looping problem is solved by switches and by routers. How do switches / routers handle link failure? (AU –ND 2010)-1 (8)

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS12. State the advantages of IPv6 over IPv4 (AU –ND 2010)-1 (8)

13. What is subnetting? Discuss. Also state which classes of IP address can be subnetted. (AU –ND 2010)-2 (8)

14. What is subnet Masking? Discuss. (AU –ND 2010)-2 (8)

15. Explain the following (AU–ND2011,AU–ND 2012)-2(i) Internet protocol-IPv4,IPv6 (ii) Routing- Unicast, Multicast routing protocols

16. Write short notes on the following (AU –ND 2012)-1 (16)a. BOOTP (ii)Multicast routing

17. Briefly explain the various routing techniques in detail. (AU –AM 2010)-1 (16)

18. Write short notes on Network Address Translation. (AU –AM 2010)-1 (8)

19. How will you transmit the packets by using Datagram approach? Explain in detail with a neat

diagram. (AU –AM 2010)-1 (8)

20. Briefly explain IGMP message format and IGMP operation in detail. (AU –AM 2011)-1 (8)

UNIT IV TRANSPORT LAYER

PART A

1.What is leaky bucket? (AU –ND 2009)-1 The input rate can vary,but the output rate remains constant.Similarly,in networking,

a technique called leaky bucket can smooth out bursty traffic. Bursty chunks are stored in the bucket and sent out at an average rate.

2.Define multiplexing and demultiplexing. (AU –ND 2009)-1

Multiplexing: Many -to- one process, Accepts messages from different processes, Differentiated by their assigned port numbers.

Demultiplexing: One -to- Many process, receives message from network layer, check the error and deliver each message to appropriate process based on port number

3. In cases where reliability is not of primary importance, UDP would make a good transport protocol. Give example of specific case? (AU –ND 2010)-1 1. TFTP-Trivial File Transfer Protocol. 2. SNMP 3. RIP4. What are the four general techniques to improve the QOS in the transport layer? (AU –ND 2009,AU – AM 2011)-2

1. Scheduling Traffic 2.Shaping 3.Admission control 4.Resource reservation5. What are the duties of transport layer? (AU –ND 2011)-1 The services provided by the transport layer

1. End-to- end delivery 2.Addressing 3.Reliable delivery 4.Flow control 5.Multiplexing6. What is meant by segment? (AU –ND 2011)-1

At the sending and receiving end of the transmission, TCP divides long transmissions into smaller data units and packages each into a frame called a segment.

7. Explain the main idea of the UDP. ? (AU –ND 2012)-1

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS(i) User Datagram Protocol is called a connectionless, unreliable transport protocol-does not add

anything to the services of IP except to provide process to process communication instead of host-to-host communication.

(ii) It performs very limited error checking.(iii)UDP is a very simple protocol using a minimum of overhead.

8. What is meant by quality of service? (AU –ND 2012)-1The quality of service defines a set of attributes related to the performance of the connection. For each connection, the user can request a particular attribute each service class is associated with a set of attributes.

9. What is the purpose of TCP push operation? (AU –AM 2010)-1(i) The sending TCP must not wait for the window to be filled. It must create a segment and send it

immediately.(ii) Push bit to let the receiving TCP know that the segment includes data must be delivered to the

receiving application program as soon as possible.10. Name the three types of socket interfaces. (AU –AM 2010)-1 There are several Internet socket types available:

Datagram sockets, also known as connectionless sockets, which use User Datagram Protocol (UDP)

Stream sockets, also known as connection-oriented sockets, which use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP).

Raw sockets (or Raw IP sockets), typically available in routers and other network equipment. Here the transport layer is bypassed, and the packet headers are made accessible to the application.

11. Suppose a TCP connection is transferring a file of 5000 bytes, the first byte is numbered 10001. What are the sequence numbers for each segment if data are sent in five segments, each carrying 1000 bytes? (AU –AM 2011)-1

Segment 1 Sequence Number: 10,001 (range: 10,001 to 11,(00) Segment 2 Sequence Number: 11,001 (range: 11,001 to 12,000) Segment 3 Sequence Number: 12,001 (range: 12,001 to 13,000) Segment 4 Sequence Number: 13,001 (range: 13,001 to 14,000) Segment 5 Sequence Number: 14,001 (range: 14,001 to 15,000)

13. What is three way hand shaking? (AU –MJ 2013)-1 The connection establishment in TCP in called three ways hand shaking.

14. Differentiate constant bit rate and variable bit rate. (AU –MJ 2013)

Sl.no Constant bit rate Variable bit rate

1 Fixed size Variable size

2 Data rate does not change Data rate change in time

3 Average rate and peak rate are same Average rate and peak rate are different

4 Traffic is easy to handle Traffic is difficult to handle15. What is supernetting? (AU –AM 2010)-1

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS1. Supernetting refers to increase host and reduce the subnets. It means reduce the network bits

and increase the host bits. 2. Supernetting is the collection of the subnets. In supernetting, an organization can combine

several class C blocks to create a larger range of addresses. 16. Why the congestion occurs in network? (AU –JM 2012)-1

If the load on the network –the number of packets sent to the network is greater than the capacity of the network-the number of packets a network can handle.

17. What is meant by Socket? (AU –JM 2012)-11. A network socket is an endpoint of an inter-process communication flow across a computer

network. Today, most communication between computers is based on the Internet Protocol; therefore most network sockets are Internet sockets.

2. The combination of an IP address and a port number is called s socket address. 18. What is function of transport layer?

(i)The protocol in the transport layer takes care in the delivery of data from one application program on one device to an application program on another device. (ii)They act as a link between the upper layer protocols and the services provided by the lower layer.

19. What is the difference between network layer delivery and the transport layer delivery?1. Network layer delivery: The network layer is responsible for the source-to-destination

delivery of packet across multiple network links.2. Transport layer delivery: The transport layer is responsible for source-to-destination

delivery of the entire message.20. What are the four aspects related to the reliable delivery of data? Four aspects are (i) Error control (ii) Sequence control

(iii) Loss control (iv) Duplication control21. What is meant by segmentation?

When the size of the data unit received from the upper layer is too long for the network layer datagram or data link layer frame to handle, the transport protocol divides it into smaller usable blocks. The dividing process is called segmentation.

22. What is meant by Concatenation?The size of the data unit belonging to single sessions are so small that several can fit together into a single datagram or frame, the transport protocol combines them into a single data unit. The combining process is called concatenation.

23. The transport layer creates the connection between source and destination. What are the three events involved in the connection?For security, the transport layer may create a connection between the two end ports. A connection is a single logical path between the source and destination that is associated with all packets in a message. Creating a connection involves three steps:

(i) Connection establishment (ii) Data transfer & Connection release.24. What is meant by congestion?

Congestion in a network occurs if user sends data into the network at a rate greater than that allowed by network resources.

25. Why the congestion occurs in network?Congestion occurs because the switches in a network have a limited buffer size to store arrived packets.

26. What are the two categories of QOS attributes?The two main categories are(i) User Oriented (ii) Network Oriented

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS27. List out the user related attributes?

User related attributes are(i) SCR – Sustainable Cell Rate (ii) PCR – Peak Cell Rate(iii) MCR- Minimum Cell Rate (iv) CVDT – Cell Variation Delay Tolerance

28. What are the networks related attributes?The network related attributes are,(i) Cell loss ratio (CLR) (ii) Cell transfer delay (CTD)(iii) Cell delay variation (CDV) (iv) Cell error ratio (CER)

29. What is the difference between service point address, logical address andphysical address? (i)Service point addressing   The transport layer header includes a type of address called a service point address or port address, which makes a data delivery from a specific process on one computer to a specific process on another computer.(ii)Logical addressing    If a packet passes the network boundary we need another addressing to differentiate the source and destination systems. The network layer adds headers, which indicate the logical address of the sender and receiver.(iii)Physical addressingIf the frames are to be distributed to different systems on the network, the data link layer adds the header, which defines the source machine’s address and the destination machine’s address.

30. What are the rules of non boundary-level masking?1. The bytes in the IP address that corresponds to 255 in the mask will be repeated in the

subnetwork address2. The bytes in the IP address that corresponds to 0 in the mask will change to 0 in the

subnetwork address.For other bytes, use the bit-wise AND operator. 31. Define Gateway.

A device used to connect two separate networks that use different communication protocols 32. What is LSP?

In link state routing, a small packet containing routing information sent by a router to all other router by a packet called link state packet.

PART B

1. Explain in detail about integrated services and impact of QOS . (AU –AM 2010)-1 (8)

2. With a neat sketch explain User Datagram format. (AU –AM 2010)-1 (8)

3. With a neat sketch explain TCP segment format. (AU –AM 2010)-1 (8)

4. Draw the TCP header and explain its fields. (AU –MJ 2012)-1 (8)

5. What are the functions performed by UDP? What are the fields in its header?

(AU –MJ 2012) -1 (8)

6. Explain the sliding window protocol. (AU –ND 2009)-1 (8)

7. Explain the two categories of congestion control in detail. (AU –ND 2009)-1 (8)

8. What is QOS in internetworking? State the techniques to improve QOS.(AU –ND 2010)-1 (8)

9. Explain TCP connection, Termination and error control mechanism. (AU –ND 2010)-1 (8)

10. Discuss the congestion control mechanism and transmission control protocol with neat

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSsketches. (AU –ND 2011)-1 (8)

11. Explain the leaky bucket and token bucket algorithm with flow charts. (AU –ND 2011)-1 (8)

12. Explain the congestion control technique in TCP. (AU –ND 2012)-1 (8)

13. Explain the segment formats for TCP and UDP. (AU –ND 2012)-1

14. How is IP address space divided into different classful addresses? Explain.

(AU –AM 2010)-1 (8)

15. What do you understand by “3-way hand shake” in TCP? Explain (AU –AM 2011)-1 (8)

16. Explain the features of TCP. (AU –AM 2011)-1 (8)

17. Elaborate the characteristics of QOS. (AU –AM 2011)-1 (8)

18. Explain the following characteristics. (AU –MJ 2013)-1 (8)

(i) Reliability (ii) Delay (iii) Jitter (iv)Bandwidth

19. Explain how connection is established and released in TCP with a neat sketch.

(AU – MJ 2013)-1 (8)

20. Explain the default timer mechanism followed in TCP. (AU –MJ 2013)-1 (8)

UNIT – V APPLICATION LAYER

PART A

1. What is DNS and the purpose of DNS? (AU –MJ 2012)-1 The DNS converts the Domain names into IP numbers -Domain Name System can map a name

to an address and conversely an address to name. Divisions of DNS 1.Generic domains 2.Country domains 3.Inverse domains

2. What is the function of SMTP? (AU –MJ 2012)-11. The TCP/IP protocol supports electronic mail on the Internet is called simple Mail

Transfer(SMTP). It is a system for sending messages to other computer users based on e-mail addresses.

2. SMTP provides mail exchange between users on the same or different computers.3. Mention the significance of network security. (AU –AM 2010)-1

1. Privacy: The sender and the receiver expect confidentiality.2. Authentication: The receiver is sure of the sender’s identity and that an imposter

has not sent the message. 3. Integrity: The data must arrive at the receiver exactly as it was sent.4. Non-Reputation: The receiver must able to prove that a received message came

from a specific sender.4. Define cryptography and need for cryptography. (AU –ND 2009, AU –AM 2010)-2 Cryptography is the science and art of transforming messages to make them secure and immune to attack. 5. What is anonymous FTP? (AU –ND 2010)-1

1. FTP- File Transfer Protocol. To download and upload files from and to the server.

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS2. FTP establishes two connections between the hosts. One connection is used for data

transfer, the other for control information. The control connection uses very simple rules of communication. The data connection needs more complex rules due to the variety of data types transferred.

6. What is substitutional and transposition encryption. (AU –ND 2011)-1Substitutional: 1. A character level encryption in which each character is replaced by another character in the set. 2. Substition ciphers encrypt plaintext by changing the plaintext one piece at a time. The Ceasar

Cipher was an early substitution cipher. In the Caesar Cipher, each character is shifted three places up. Therefore, A becomes D and B becomes E, etc...

Transpositional: 3. A Character level encryption in which the characters retain theirplaintext but the position of the

character changes.4. Transposition ciphers encrypt plaintext by moving small pieces of the message around.

Anagrams are a primitive transposition cipher. This table shows "VOYAGER" being encrypted with a primitive transposition cipher where every two letters are switched with each other:

7. What is digital signature? (AU –ND 2011)-1Digital signature is a method to authenticate the sender of a message. It is similar to that of signing transactions documents when you do business with a bank. In network transactions, you can create an equivalent of an electronic or digital signature by the way you send data.

8. How is a symmetric key different from public key? (AU –ND 2012)-1(i)In secret key, the same key is used by both parties. The sender uses this key and an encryption algorithm to encrypt data; the receiver uses the same key and the corresponding decryption algorithm to decrypt the data. (ii)In public key, there are two keys: a private key and a public key. The private key is kept by the receiver. The public key is announced to the public.

9. Discuss the three main divisions of the DNS. (AU –ND 2012)-1 Main divisions of DNS 1. Generic domains 2.Country domains 3.Inverse domains

Generic domain: Define registered hosts according to their generic behavior, uses generic suffixes.

Country domain: Uses two characters to identify a country as the last suffix. Inverse domain: Finds the domain name given the IP address.

10. What is the purpose of inverse domain? (AU –AM 2010)-1 To finds the domain name given the IP address.

11. What is the function of P-Box? (AU –AM 2010)-1In cryptography, a permutation box (or P-box) is a method of bit-shuffling used to permute or transpose bits across S-box inputs, retaining discussion while transposing.

12. Why do we need POP3 or IMAP4 for E-mail? (AU –AM 2011)-1(i) Workstations interact with the SMTP host, which receives the mail on behalf of every host in the organization, to retrieve messages by using a client-server protocol such as Post Office Protocol, version 3(POP3). (ii) POP3 is used to download messages from the server, the SMTP client still needed on the desktop to forward messages from the workstation user to its SMTP mail server.

13. Differentiate cipher text and plaintext. (AU –AM 2011)-1 Cipher text  is the unreadable output of an encryption algorithm  Plain text  means its text that hasn't been formatted (i.e., a plain text file)

14. State the difference between fully qualified and partially qualified domain name. (AU –MJ2013)-1

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS1. Fully Qualified Domain Name (FQDN)

 The domain names always read from the node up to the root.  Hence the last label is the label of the root (null).If a label is terminated by a null string, then it is called fully qualified domain (FQDN) that contains the full name of a host. Ex:CS.princedon.edu

2. Partially Qualified Domain Name (PQDN)If a label is not terminated by a null string, then it is called as partially qualified domain name (PQDN).  It starts from the node, but it does not reach the root. Example: CS

15. Discuss the basic model of FTP.1. The client has three components: the user interface, the client control process, and the client

data transfer process. 2. The server has two components: the server control process and the server data transfer

process. The control connection is made between the control processes. The data connection is made between the data transfer processes.

16.What is the difference between a user agent (UA) and a mail transfer agent (MTA)?(i)The UA prepares the message, creates the envelope, and puts the message in the envelope. (ii)The MTA transfers the mail across the Internet.

17. How does MIME enhance SMTP?(i) MIME is a supplementary protocol that allows non-ASCII data to be sent through SMTP. MIME transforms non-ASCII data at the sender site to NVT ASCII data and deliverers it to the client SMTP to be sent through the Internet. (ii) The server SMTP at the receiving side receives the NVT ASCII data and delivers it to MIME to be transformed back to the original data.

18.Write down the three types of WWW documents.The documents in the WWW can be grouped into three broad categories: static, dynamic and active.

1. Static: Fixed-content documents that are created and stored in a server.2. Dynamic: Created by web server whenever a browser requests the document.3. Active: A program to be run at the client side.

19. What is the purpose of HTML?(i) HTML is a computer language for specifying the contents and format of a web document. (ii)It allows additional text to include codes that define fonts, layouts, embedded graphics and hypertext links.

20.Define CGI.(i)CGI is a standard for communication between HTTP servers and executable programs. (ii)It is used in crating dynamic documents.

21. What are the advantages & disadvantages of public key encryption? Advantages:

a) Remove the restriction of a shared secret key between two entities. Here each entity can create a pair of keys, keep the private one, and publicly distribute the other one.

b) The no. of keys needed is reduced tremendously. For one million users to communicate, only two million keys are needed.

Disadvantage:a) If you use large numbers the method to be effective. Calculating the cipher text using the long

keys takes a lot of time. So it is not recommended for large amounts of text.22. What are the advantages & disadvantages of secret key encryption? Advantage:

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKSSecret Key algorithms are efficient: it takes less time to encrypt a message. The reason is that the key is usually smaller. So it is used to encrypt or decrypt long messages.Disadvantages:a) Each pair of users must have a secret key. If N people in world want to use this method, there needs to be N (N-1)/2 secret keys. For one million people to communicate, a half-billion secret keys are needed.b) The distribution of the keys between two parties can be difficult.

23.What is wwwb) World Wide Web is: all the resources and users on the Internet that are using the Hypertext Transfer

Protocol (HTTP)PART B

1. With a relevant example discuss how the domain space is divided? And list the risks faced by messages that are transmitted over the internet. (AU –ND 2010)-1 (8)

2. Distinguish between a fully qualified domain name and partially qualified domain name. Give relevant example. (AU –ND 2010)-1 (8)

3. What is the acronym SMTP, FTP, WWW and HTTP stands for? Explain their uses and state the strengths and weaknesses of each of them. (AU –ND 2010)-1 (8)

4. Explain in detail RSA-PUBLIC KEY CRYPTOGRAPHY with examples. (AU –ND 2009)-2 (8)

5. How does the E-mail system work? Explain about E-mail services. (AU –ND 2009)-1 (8)

6. Explain the functioning of DNS. (AU –AM 2010, AU –ND 2011, AU –AM 2010)-3 (8)

7. Explain the Simple Mail Transfer Protocol. (AU –AM 2010)-1 (8)

8. Explain the various services provided by security. (AU –AM 2010)-1 (8)

9. What are the servers involved in Kerberos protocol? Explain in detail.(AU –AM 2010)-1 (8)

10. Describe how SMTP protocol is used in E-mail applications. (AU –AM 2011)-1 (8)

11. Explain about Digital Signature. (AU –AM 2011)-1 (8)

12. Discuss in detail about HTTP. (AU –AM 2010, (AU –ND 2012)-2 (8)

13. Explain in detail about WWW architecture. (AU –MJ 2012, AU –MJ 2013)-2 (8)

Diagram

Explanation

14. Write short notes on: (AU –JM 2012, AU –ND 2012)-2 (8)

(i) FTP (ii) Symmetric key.

15. Explain the concept of cryptography and discuss about symmetric key and public key algorithms. (AU –ND 2011)-1 (8)

Definition for Criptography. Explain Symmetric Key Algorithm. Public Key Algorithm.

--------------------

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN

Subject Code / Name:EC2352 COMPUTER NETWORKS

By : P.Raja Pirian. M.E.,M.B.A., KCE/ECE/QB/III YR/CN